On a familiar jungle planet, two Space Security agents hide under cover of thick foliage. The jungle is alive with sinister sounds, both animal and otherwise. In command is Bret Vyon - tough and no-nonsense. His comrade is Kert Gantry. He is more cautious and fearful; understandable as his leg is badly injured and he is having trouble moving. Both men are constantly scanning their surroundings.

Vyon is working with an R/T device, trying desperately to reach Central Communications on Earth with no success. Gantry is sure "they" are nearby and will find them before communications can be established. Vyon is grimly positive, ready to fight to the death to get his message through. They must contact Earth before they are found or the whole solar system is finished!

Back on Earth, Agents Roald and Lizan work at Central Communications. It is a quiet evening and both are bored. In order to pass the time, Roald wants to tune in to the Mars-Venus game but Lizan wants to watch a speech by Mavic Chen, Guardian of the Solar System. Roald suggests a compromise - checking out the evening news in order to see a bit of both things. Lizan agrees, but worries about missing some incoming calls. Roald isn't worried, noting that the next call isn't due for another 20 minutes. That's the call from Gantry and Vyon. Their patrol is out looking for Agent Marc Cory, who disappeared near the planet Kembel. It should be a routine evening. Neither agent has noticed the flashing light indicating Vyon's emergency communication.

The two are distracted when the news comes on and there is Mavic Chen, standing near his Spar spacecraft on its launch pad as he is being interviewed. He explains that after some difficult but successful mineral negotiations with the fourth galaxy, he's off on holiday. Roald and Lizan banter about this plan, Roald clearly jealous of Chen's freedom and his "elegant" spacecraft, despite the fact that he doesn't care much for the man himself. In fact, he listens with contempt as Chen passes on his final thoughts before departing - extolling the peace in the solar system in this year of 4000, and of his hopes for its continuation. As the report ends, Lizan thinks she sees an indication of a call coming through, but then there is nothing. Perhaps she was only imagining things.

Meanwhile, Gantry and Vyon are on the move, fleeing from something in the jungle. They are on Kembel, searching for any trace of the lost agent Marc Cory. Gantry, utterly exhausted, stops to rest. He knows their pursuers are nearby and they have little hope of evading them. A noise from the jungle confirms this for both of them. Vyon is keen to keep moving, trying to stay ahead of them, but Gantry refuses to move because of his leg. It is much worse now. Even if he did try, he is certain that he would only succeed in falling on a spiked Varga plant and then turn into one. Gantry becomes convinced that this is how Marc Cory died. Vyon tries to reason with him, saying that they must continue to try to communicate with Earth, but that does nothing to change Gantry's mind. He urges Vyon to go on without him, as he would only slow them down, but when Vyon refuses, Gantry draws his gun and orders Vyon to leave. There is no time for Vyon to argue and he is certain that the wild-eyed Gantry is serious in his intent. He must leave his partner to die in order for him to live long enough to get his message through to Earth. With no other choice, Vyon moves off.

Alone now, Gantry moves into a better position and clutches his weapon tightly, knowing that it will be no good against his hunters, but perhaps it will buy Vyon a bit of valuable time. He utters a silent wish to Vyon for luck and then calls out into the jungle. For a long, nerve-wracking moment, they do not come. The anticipation sets him on edge. Just when he thinks he may be safe for the moment, two Daleks burst through the foliage. There is no hesitation before they fire and kill him. Only one more fugitive to go.

Vyon, haring through the jungle, takes an incautious step and trips, the precious radio falling from his hands and smashing on the ground. It is useless. However, Vyon has no time to despair as he is distracted by a strange noise nearby.

Vyon watches as the TARDIS materializes in the jungle. The Doctor's path has finally connected with the Daleks on Kembel. The Doctor emerges into the gloom and noise, Katarina standing fearfully behind him. They are looking for medicine to help the injured Steven, but Katarina seems sceptical that they will find help here. The Doctor sends her inside with instructions to close the door securely behind her. He explains to the naïve girl that he has a key and can get in when he returns. He even shows her the key, unaware that they are being observed. The Doctor tells Katarina to look after Steven, then he heads off to explore.

He moves through the jungle to a point where he can see through the trees. In the distance and far below, he catches sight of part of a complex of buildings - perhaps a city, although it seems an odd place for one. Perhaps he might find some help for Steven there. He starts to move forward but is stopped when he feels a gun pressed into his back. Bret Vyon has been following him since he left the TARDIS. He wants the key or he will kill the Doctor.

Inside the ship, Steven drifts in and out of consciousness. Katarina tries to assure him that he will be fine, but Steven is feverish and confused. He remembers Troy and Vicki, but not much else. It doesn't help that Katarina believes the Doctor to be a god transporting her through "the underworld". Steven lapses back into unconsciousness just as the doors open and Bret Vyon enters. He looks around in awe of his surroundings.

The trusting Katarina assumes Vyon has been sent by the Doctor, and she urges him to cure Steven. Vyon recovers himself quickly and orders her to close the doors. He tells her he will help Steven, but they must get back to Earth first. Katarina is not concerned when Vyon wants to operate the ship because she knows that only the Doctor can work his "temple". In the face of this extraordinary technology, Vyon is at a loss as to his next move.

Outside the ship, the Doctor dusts himself off after his altercation with Vyon. Ever the foe of violence, the Doctor is sure that this violent young man is no match for his wits. The Doctor reaches the ship to find Vyon's first mistake -- leaving the key in the door. Overpowering him will be even easier than he first thought.

However, inside the ship, Steven has come to again and taken matters into his own hands. Seeing the armed stranger poking round the controls, Steven finds the strength to raise himself up and launch himself at the man. He succeeds in knocking Vyon out. Katarina rushes to help Steven.

At the door, the Doctor pauses before entering as a loud roar issues from somewhere nearby. In the sky above, he sees a spaceship flying low. The Doctor wonders if it has to do with the city or the man who attacked him. There is a mystery here on this planet and he must have answers.

In the city, the Daleks are pleased with the arrival of the new ship.

Inside the TARDIS, the Doctor has made short work of subduing the intruder by placing him in a chair. When Vyon comes to, he cannot move or leave the chair, even though he is not restrained. The Doctor calls his invention a "magnetic chair", with a force field strong enough to restrain a herd of elephants. Sure that Vyon is safely immobile, the Doctor checks on Steven. He is feverish and still in need of medicine. The Doctor tells Katarina not to worry and then heads off.

On his way to the city, the Doctor happens upon a decomposed body. It is a skeleton in the remains of a black uniform. Beside the body is a discarded tape recorder, badly damaged. The Doctor removes and pockets the tape and moves quickly on, unaware that he has learned the fate of Marc Cory and now carries his vital message.

The Doctor arrives at an observation point above the city, an uneasy feeling growing in him as he approaches. The same spaceship he saw earlier eases to a landing on a pad on the outskirts. There is a large collection of other ships already there. The Doctor watches this, his worst fears confirmed when a tannoy announces the ship's arrival. The voice is that of a Dalek!

In the TARDIS, Vyon tires of trying to break free of the chair and turns to Katarina. She tells him that Steven has an infection due to his wounds and he offers her help in the form of tablets in his first aid kit. She is fearful that he is trying to fool her, but she is desperate to help Steven. She hesitates a long time, having no doubt that the Doctor will be angry with her for disobeying him. But she follows Vyon's instructions and gives Steven the strange "tablets". Vyon can only hope that the Doctor will get back quickly.

In the Dalek city, two Daleks go out to greet the arrival of their newest ally. From the shadows, a human being steps forward, announcing how honoured he is to be a part of their plan to conquer Earth. It is Mavic Chen, Guardian of the Solar System, and he is an ally of the Daleks!

Having seen and heard enough, the Doctor leaves his vantage point above the Dalek city and heads back toward the TARDIS.

The Daleks at the TARDIS inform the Dalek Supreme of further intruders on the planet. They are informed that "Operation Inferno" is to be put into execution immediately, far ahead of schedule. All patrols are to withdraw to safety areas in preparation. The TARDIS is left alone as the Daleks roll away. The Doctor realises that the doors of his ship are open.

Mavic Chen relaxes in the Dalek city, awaiting the resumption of the conference of Dalek allies. He is addressed by Zephon, Master of the Fifth Galaxy. Zephon is immediately adversarial, arguing over Chen's casual observation that they nearly met before. Chen tries again, speaking casually of the notes from the previous allied meetings. He is pleased at the Daleks' plan and praises their "genius for war". But Zephon gets quickly to his point he is suspicious of Chen's motives for joining the allies. He is master of the very influential solar system after all. Chen speaks somewhat idly of his desire to rule the entirety of the Milky Way galaxy. However, his casual manner belies his true aims to power. When Zephon persists in questioning him, Chen turns the discussion to Zephon's own problems - namely two recent coup attempts against him. This distraction allows Chen to gain the upper hand in the discussion and he urges Zephon to take a walk outside with him to further discuss these issues.

Chen's caution proves well-founded. From the shadows, a Dalek emerges. It has been listening in. It reports to the Dalek Supreme that Chen's ambitions clearly exceed his usefulness to the plan. But the Dalek Supreme is unconcerned. When Chen has served his purpose, he, like all the others, will be destroyed. No power can stand against the Daleks.

In the jungle, Steven and Katarina hide. They were forced to leave the TARDIS due to the arrival of the Daleks earlier. Vyon is nowhere to be seen. Steven is much recovered, thanks to the tablets Vyon gave him, but his mind is still cloudy. He is shocked to learn the Daleks are here. They scan the jungle warily, unsure what to do next. Shortly, though, the Doctor appears, surprised to find them outside. Katarina tells the Doctor the whole story of Vyon, the tablets and "the evil ones" - the Daleks. She is sure he will be angry at her for releasing Vyon from the magnetic chair, but it seems he is most pleased that his two companions are all right. He is also glad that Vyon took the time to help Steven, despite the fact that the Doctor had incapacitated him. Neither Vyon nor Katarina could have known that the Daleks couldn't get into the TARDIS and he does not blame the girl for releasing Vyon. Instead, the Doctor is grimly focused on the danger facing them and the work they have yet to do.

Elsewhere in the jungle, Operation Inferno has begun. A group of Daleks have been fitted with pyro-flames. When ordered, they activate the flames and move off into the jungle, setting fire to the plants and undergrowth. The jungle is to become an inferno.

The Doctor and his friends are joined by Bret Vyon a short time later. He has seen Operation Inferno in action and reports this to the Doctor. In fear of their lives, the uneasy group must work together. The Doctor's first instinct is to return to the TARDIS as it is the safest place they can go, but Steven is worried that they will be caught in a trap. Perhaps the flames are meant to drive them back, right into the clutches of the Daleks. This disagreement grows into a full-scale row, all the while the sounds of burning plants grow. Frustrated, Vyon shouts out to shut them both up. He doesn't care what they do as long as he can warn Earth what is happening here. But the Doctor tries to regain the upper hand by insisting that they themselves must stop the Daleks, whatever their plans may be.

Meanwhile, the jungle continues to be consumed in flames.

The Doctor and Vyon argue over their plan of action. The Doctor seems unconcerned over a Dalek attack on Earth, as such an invasion was already dealt with in 2157. The Daleks wouldn't try that again. He fears that there is a much larger and more dangerous plan being put into action. And when the horizon begins to glow with fire and smoke, he knows they must act quickly. The Doctor leads his group toward the Dalek city. Vyon is horrified, but the Doctor is sure that is the last place the Daleks would look for them. He urges them onward; Vyon follows reluctantly.

Chen and Zephon have strolled outside and now watch as the jungle burns in the distance. Chen marvels at the primitive power of the flame, but Zephon thinks it a poor substitute for ultrasonics. Chen appears eager to return to the meeting room, and Zephon chides him for kowtowing to the Daleks. Eager to show his independence, Zephon brags about his indispensable contribution to the plan. It was he who got the masters of Celation and Beaus to join the alliance and the plan could not go forward without him.

Chen dismisses this and heads back inside. However, Zephon is certain the meeting will not begin without him and decides to wait outside until he is good and ready. But he has overestimated his worth. The Daleks have been eavesdropping and have decided that Zephon's usefulness is over. But did Chen set him up to be found out?

The Doctor and company reach the Dalek city without incident. They are awed at the sight of the landing pad and all the various ships there. Vyon recognizes Mavic Chen's Spar spaceship and knows his presence here with the Daleks means trouble. The Doctor seems to ignore this, focusing instead on the question of whether Vyon can fly the ship. When he says he can, the Doctor decides they must capture the ship in order to get to Earth and warn someone in authority. Moving ahead, they find Zephon standing alone outside. Vyon silently motions to the others to stay put while he moves forward. When Zephon turns his back, Vyon leaps on him and knocks him out.

In the conference room, Mavic Chen joins the other delegates already gathered. The only one absent is Zephon and the Dalek Supreme is impatient to get started. A Dalek is sent to find him.

With Zephon out of the way, Vyon is ready to head for Chen's ship, but the Doctor still wants more information and now he knows how to get it. He decides to disguise himself with Zephon's helmet and cloak and to attend the meeting that is clearly happening here. His companions are dead set against this, but the Doctor will not be dissuaded. Vyon, Steven, and Katarina are to commandeer the Spar spaceship and wait for the Doctor to join them.

The Doctor gives Vyon the battered tape he found for safe keeping. Vyon seems to recognizes it, but has no time now to discuss it. He is ready to capture Chen's ship. The Doctor tells them to wait for him as long as they can, but if they hear any sort of uproar, they must get away with our without them. Earth must be warned about the Daleks no matter what. Vyon is impressed at the Doctor's bravery, but the Doctor says he is only doing what has to be done and sets about removing Zephon's cloak.

The search Dalek goes to find Zephon. He finds the Doctor just as he gets inside the building and is fooled by the disguise. Without a word, the Doctor follows the Dalek into the conference room. Meanwhile, Vyon, Steven, and Katarina wish the Doctor good luck before moving off toward Chen's ship.

Inside the conference room, the Doctor is brought in. Representative Trantis is critical of "Zephon's" apparent contempt, but Representative Chen seems more concerned that "Zephon" cannot seem to find his proper place at the table. Chen directs him to the seat next to him at the low round table. The meeting can at last begin.

The Dalek Supreme announces that "the time destructor" has been completed and requires only its core to be fitted to become fully operational. All of the delegates indicate their approval by pounding the table. Then Chen addresses the meeting. He produces as small, silvery cylinder which he announces with some degree of smugness is the core of the time destructor. It is a full emm of taranium, the rarest mineral in the universe. It is available only on one of the dead worlds of the solar system, and it has taken 50 years of secret mining to produce this much. But now that he - and he alone - has produced the taranium, the Daleks' planned conquest of the entire universe can begin.

Vyon and the others make their way to the Spar easily and rush inside. Two technicians inside surrender to Vyon when they see he is armed and means business. Steven ties them up then tosses them outside. Both Steven and Vyon are sure the men will not be found right away. They start to prepare the ship for takeoff while Katarina urges the Doctor to hurry.

However, Zephon has come to and found an emergency alarm button. The klaxon sounds throughout the city. In the conference room, the delegates react with shouts and confusion. The Doctor takes advantage of the chaos to grab the taranium core and run. He is out of the room before Chen can shout for assistance. The Daleks roll off in pursuit of "Zephon".

A signal indicates that the outer airlock door has failed to close. They cannot take off or they will be destroyed. The engine whine stops rising. Steven races to the airlock to see the Doctor running across the landing pad toward them. He forces the door to stay open even as it tries to close on him. The Doctor races to the ship, Daleks in pursuit. Steven helps the Doctor aboard and they urge Vyon to take off. They do so, the Spar ship leaping quickly into the air.

In the Dalek control room, the ship's launch is monitored as it reaches escape velocity. The Dalek Supreme orders automatic trackers locked onto the ship, but does not authorize the use of force, even though the Daleks could easily destroy the Spar. The intruders must be captured alive, at least until the taranium is recovered. Instead, the Dalek Supreme orders a neutronic randomiser prepared.

The Doctor congratulates Vyon for getting them off safely, but chides him for thinking that the Doctor wouldn't make it. The Doctor shows the silvery cylinder to his companions and tells them the Daleks' plans are useless without it. He tells them the Daleks intend to take over the entire universe, starting with Earth, the solar system, the Milky Way, and then expanding to the outer galaxies. All of this is thanks to the cooperation of all the outer galaxies' leaders. Mavic Chen has sold out the solar system for more power. They must get back to Earth and warn someone in authority who can stop Chen.

Katarina does not understand all of this and is mystified at how she can get back to Earth as she believes she's already dead. In response to Vyon's questions, Steven simply tells him she's from Troy and doesn't comprehend. Now Vyon's confused! Steven dismisses his questions and turns back to the cylinder, the vital taranium core. Surely if they have this, the Daleks are powerless to carry out their plans and the danger is over. But the Doctor assures them all that this element is so rare and so powerful that neither Chen nor the Daleks will give it up without a fight. And if they have it, they can easily conquer the universe with their time destructor - one of the most evil weapons ever devised.

Back on Kembel, the Daleks are interrogating Representative Zephon. They have quickly decided that it was his negligence which allowed the intruders access to the conference. Chen adds arrogance to Zephon's sins, saying he should have come inside instead of waiting where he could be attacked. Zephon tries to protest, but he sees that he doesn't have a leg to stand on. Instead, he turns the accusation against Chen, saying that the intruders must have come from the solar system - that is the only way they could have known that the taranium was here. No one else but Chen and the Daleks knew of its existence. However, he has no proof of this and Chen has no real motive to have the core stolen. He would be useless to the Daleks without it. Faced with this, Zephon has no response other than to attack the Daleks' security measures for allowing the intruders to get so close in the first place. Predictably, the Daleks do not accept the argument and find him guilty of negligence. Realizing that his life is in danger, Zephon invokes the unity of the alliance, saying that Celation and Beaus will leave the group if he is forced out. This is proven false when all of the other representatives align with the Daleks against him. Underestimating the Daleks, Zephon believes he can simply leave. He turns and walks arrogantly away, heading for his spaceship. For a moment, it looks like his arrogance has saved him and he nearly reaches the door. Then the Daleks fire and execute him.

The Daleks then turn to the location of Chen's Spar. It is nearing the influence of the planet Desperus. The Dalek Supreme orders a pursuit ship prepared and then gets ready to activate the randomiser.

On board the Spar, the Doctor has opened up the cylinder containing the taranium, checking over the precious mineral. He and Steven observe it through heavily-shielded goggles as taranium gives off an intense light that would otherwise blind them. Steven wonders about their next move and is surprised when the Doctor says they must do nothing. He explains that the Daleks' plans are on hold without the taranium and as long as he holds it, he has the upper hand. By doing nothing with it, he controls this very dangerous game. Closing up the cylinder, the Doctor turns to Vyon to retrieve the recording device he found in the jungle and prepares to play it. He makes sure Katarina is there to observe the "miracle" of an electronic tape player.

Discussing the tape, the Doctor talks of the remains he found next to the recorder - a humanoid. He believes it may be someone who found out more about the Daleks' plans and was killed because of it. Vyon confirms it's Marc Cory's tape, but wonders how the Doctor found it when he and Gantry couldn't. The Doctor tetchily explains that both Vyon and the Daleks were led astray by the shifting of the jungle - aggressive plants like that ebb and flow, creating mazelike conditions which change often, covering and uncovering patches of ground at intervals. He then proceeds to play the tape. Cory's voice explains that the Daleks plan the complete destruction of the solar system and that a warforce is being assembled. Then the tape cuts out. Vyon is saddened, knowing his comrade gave his life to record a message that was never received. However, the Doctor points out that it was received - by them! They must get the message to Earth, especially knowing so much more than Cory did. And he knows that the Daleks will stop at nothing to prevent them.

Sure enough, the Daleks have tracked the Spar as it reaches its closest point to the planet Desperus. It is then that they activate the randomiser.

The Doctor tells Vyon that they must find someone on Earth they can trust, and someone who is highly-placed enough to help them. Vyon suggests Karlton, head of Space Security, but he is friends with Chen and may even be part of the plot. Their conversation is suddenly derailed when Vyon loses control of the ship and it lurches crazily. They've changed course and increased speed, heading for the nearby planet. Vyon recognizes it on sight -- it is Desperus, a penal planet used by the solar system to house its most dangerous criminals. There is no one to help them if they crash there. They'll be left to rot for the rest of their lives. That is, if they don't die in the crash, as the ship is now completely out of Vyon's control.

But the Daleks do not want the fugitives to crash. They must be kept alive until the taranium is recovered. The Daleks impose remote control over the ship and decrease its velocity for a soft landing. The pursuit ship is standing by. Chen congratulates the Dalek Supreme on a very effective operation, however he points out that the taranium has not yet been recovered. It is not over yet. The Dalek Supreme turns on Chen, suggesting as Zephon did that the fugitives are known to him. They did steal his ship after all and they clearly know how to operate it. But Chen points out that his ship - having arrived last - was the obvious one to steal as it was the one which could get out most quickly. But he offers to return to Earth and investigate. If the intruders are from Earth, he will deal with them quickly and quietly from there. Amazingly, the Daleks agree, even offering to provide him with another Spar so as not to arouse suspicion. Secretly, he breathes a sigh of relief at getting away from the Daleks' scrutiny. He promises to return once the core has been recaptured.

Vyon is confused at their sudden change in velocity. They'll be able to make a soft landing, but he doesn't know how. Unfortunately, the Doctor does. He realizes that the Daleks are controlling the ship and that it means they will soon be arriving on Desperus to hunt them down.

Desperus is true to its name - a desperate place full of desperate men. It is a thick swamp, alive with dangerous plants and dangerous animals...and even more dangerous prisoners. But they are only prisoners in the sense that they cannot leave the planet. Otherwise, they are allowed to roam freely, armed with knives and whatever else they can find, and allying themselves with each other in roving gangs in order to find safety and sustenance. They must all beware of the Screamers, vile batlike creatures who infest this swamp, their bloodcurdling cries echoing everywhere. Whoever has the superior weapon is the leader as long as he can hang onto it. They do not live but simply survive.

One such gang is convened in a dank cave. Garge and Kirksen are led by Bors, possessor of a small but convincing knife. He constantly reminds the other two of his status as leader, but it is clear that both know he is and why. Garge only waits for his turn to claim leadership away from Bors. Both of them appear to be hardened veterans of Desperus, inured to its hellishness and adept at the survival skills required to make it through the day. Kirksen, on the other hand, is newer, younger. He has yet to move beyond the shell-shocked mania which grips all new arrivals on Desperus. It is not clear whether he'll ever make that transition at this point, or whether he'll simply disappear into the madness which claims so many of the new prisoners. He won't last long after that - they never do.

Bors, asserting his authority, orders Kirksen to fetch fuel for the dying fire. It is a test for him, a test of loyalty. After a feeble protest, Kirksen manages to swallow his fear of the darkness and the creatures outside and he starts to go. However, the trip is cut short by the arrival of a spaceship nearby. The others join him outside to watch. Garge is certain it is a Spar, not a type used by the penal authorities, and realizes it must be here by mistake. Bors is sceptical but cannot afford to ignore it. Bors and Garge grab torches and set out immediately for the landing site. Kirksen is not invited along, but grabs a torch himself and plunges into the jungle after them.

On board the Spar, the Doctor is sceptical that Vyon can override the Daleks' control and fly the antiquated ship again. Vyon assures him the needed parts are here that that this is a state of the art craft fully capable of overcoming the Daleks' influence. Steven, awe-struck by the advanced technology, sides with Vyon and even criticizes the TARDIS as being uncontrollable. The Doctor delivers a stinging retort and stalks off in a huff. Steven tells Vyon to ignore him as they set to work.

The Doctor joins Katarina, who stands in the airlock marvelling at the strange alien landscape before her. She is nearly mesmerized by it, but she has also seen something worrying - torches burning in the distance. The Doctor sees them as well, two together and one by itself a little further away. The prisoners here are obviously aware of the ship's presence and they must be prepared for an assault on the ship. The Doctor notices the swampiness of the ground and gets an idea...

On Kembel, the Daleks have pinpointed the exact location of the Spar on Desperus. These coordinates are relayed to the pursuit ship, along with orders to exterminate the fugitives as soon as the taranium has been recovered.

Meanwhile, Bors and Garge are nearing the new ship. The nervous Kirksen catches them up, much to their chagrin. Worried that they may be seen, Bors orders the torches extinguished. Garge is fearful of the Screamers as they are much more active at night, but Bors knows they cannot risk alerting the ship's crew of their presence and forces him to put out the light. Bors and Garge move out quickly, desperate to reach the landing site before any of the other prisoners reach it. Kirksen hesitates before following and immediately regrets it. Without torches, the blackness is complete and he is scared. His steps are incautious in his growing mania and he crashes recklessly through the undergrowth, right into the path of a Screamer. The shadowy creature lets out a bloodcurdling howl but does not move. It does not fear humans. Kirksen's screams mingle with the creature's as he races away at top speed, heedless of direction.

On the ship, Steven and Vyon have had some success in restoring control. Meanwhile, the Doctor has used some exposed wiring to rig up a circuit around the outer airlock door utilizing the water in the marshy ground as a conductor. He attaches the leads to a power outlet nearby, brushing off questions from Vyon. He installs Katarina at the door control switch and instructs her how to use it, but she must not activate it until he gives the order. He is pleased with his work, sure it will be sufficient to repel any potential boarders.

Bors and Garge have nearly reached the landing site. They can already see the ship through the trees. Garge has a twinge of regret at leaving Kirksen, but Bors' mind has already moved ahead to the question of how to get into the ship. He is certain that the crybaby Kirksen has run screaming back to their cave to hide his head.

Katarina has been diligently watching the horizon since the torches went out. Now she sees movement just outside the landing area and alerts the Doctor. Sure enough, Bors and Garge rush from the undergrowth and run straight for the airlock door. As soon as they are in contact with the hull, the Doctor gives the order and Katarina activates the switch. With a scream, both men are hurled away, landing unconscious in the swamp.

The noise draws Vyon's attention, but the Doctor waves him off impatiently. He has repelled the boarders. Vyon is concerned as he knows there isn't enough current there to kill anyone, and the Doctor tells him he never had any intention of killing them. He has accomplished his goal and now Vyon and Steven must accomplish theirs. He sets about rerigging the electric trap, but stops when the sounds of another ship's engines fill the air. The Daleks are here!

The Doctor urges Steven and Vyon to hurry. Luckily they are finished with the repairs and can take off. But in the excitement, the Doctor has forgotten to fully close the faulty airlock door. They can get airborne, but must close the door before they reach escape velocity. The ship rises steadily and the group is jubilant. The Doctor has seen that the Daleks have made a bad landing. They should not be able to follow right away. The fugitives have evaded the Daleks again and now they must concentrate on what they will do when they reach Earth.

Vyon reminds them all about the door and Katarina - eager to help "her lord" the Doctor - goes to secure the door as he taught her. She gets to the airlock only to find someone inside. Kirksen! He reached the ship just as its engines were powering up, stepping over the bodies of his former comrades, not even taking the time to grab Bors' knife. He entered through the unsecured door.

Panic erupts on board the Spar, everyone shouting at once. Kirksen's voice rises above the others, demanding to know where the ship is headed. When he learns they are going to Earth, Kirksen orders them to change course and head for the only planet he knows is nearby - Kembel. Vyon and Steven try to tell him of the dangers that await him on Kembel, but the crazed man won't listen. Anywhere is better than Desperus, and whoever these Daleks are, he'd rather take his chances with them. At least he'd be free. He threatens to snap Katarina's neck and then repeats his order -- take the ship to Kembel.

The Dalek pursuit ship calls in for orders. When the Dalek Supreme sees that the Spar is heading for Earth, he calls the pursuit ship back to Kembel. They cannot let the humans know that they are coming and so plan to contact Mavic Chen and have him deal with the fugitives when they reach Earth. He then orders the pursuit ship to be destroyed with all aboard for having failed to capture the Spar. Failure will not be tolerated.

The Doctor does not want to change course any more than the others. Too much depends upon their reaching Earth and warning the authorities. However, he fears for Katarina's life and so tries a desperate bluff. He tells Kirksen the ship has changed course and that he should now release the girl. Kirksen is not thinking clearly, but neither is he a fool. He doesn't believe the Doctor. Vyon joins in, telling him to look at the course readout screen. When he does so, Steven attempts to enter the airlock and rescue Katarina, but Kirksen anticipates this and closes the door from the inside, trapping himself and his hostage inside. He retreats to the farthest corner of the small chamber, right next to the outer door, and communication must take place through a talk-back system. The Doctor rashly threatens to open the outer door if Kirksen doesn't surrender, but it is a stand-off as Kirksen knows he will not kill Katarina. Vyon turns off the talk-back, hoping to isolate Kirksen. He is no longer interested in negotiation. Steven orders him to turn it on again before the man gets desperate and hurts Katarina. Vyon doesn't believe he'll do that as he'll have no bargaining chip then, but he does not resist when Steven turns the talk-back on himself.

The Doctor at last realizes that they must do as he says and take him to Kembel. The Daleks will deal with him soon enough. Steven fears that they will take great delight in "dealing" with all of them as well, but knows that the Doctor is right. To save Katarina, they must do as Kirksen says. Vyon again refuses, saying he cannot risk the safety of the entire universe for one girl. Steven reminds him that without their help, he never would have gotten off Kembel alive in the first place and that he owes Katarina this. Vyon shouts back that they probably wouldn't have survived Kembel without him either but knows that Steven is right. He starts to make the adjustments.

However, Steven turns back to the airlock and reacts in horror. Katarina has gotten one arm free from her captor and is reaching for the nearby door controls. Her struggles are desperate and Kirksen cannot control her. She is reaching for the button to open the outside door, using the knowledge that the Doctor taught her earlier. She knows what will happen when she presses the button. Steven shouts at her to stop, thinking she is unaware of what will happen, but she reaches the button and she and Kirksen are instantly blown out into space. Steven screams in horror.

Then all is quiet inside the ship. The Doctor realizes that Katarina knew exactly what she was doing and sacrificed herself to save their lives and, potentially, the lives of all the beings in the solar system. Steven is still horror-struck at the needless death, but Vyon assures him it was quick and painless. The Doctor eulogizes her bravery, even in the face of such a confusing situation. He hopes she has reached her "place of perfection" and says that he shall always remember as one of the daughters of the gods. The Spar travels on toward Earth, none of its passengers speaking a word.

Back on Kembel, Representative Trantis is displaying great audacity in questioning the Dalek Supreme. He doesn't trust Chen to retrieve the taranium core and thinks that the Daleks are wrong to trust him as well. However, the Dalek Supreme is certain that the power promised Chen will be more than enough incentive to ensure he will complete his task. Trantis wants to know more about what has been promised him, invoking his status as ruler of the largest galaxy in the alliance, but the Dalek Supreme refuses. They owe Trantis nothing. Chen will succeed and the Daleks will destroy anything or anyone that stands in their way. Trantis gets the message loud and clear.

On board the Spar, the tense silence is broken only as the ship nears Earth. The Doctor is pleased at the fact that this nightmare will soon be over, but Vyon is still cautious. He has sufficient control of the ship to land safely, but he knows they cannot land in the Central City. Chen has had plenty of time to get to Earth before them and make up some story about them. His Spar will be recognized as it arrives and they will be hunted down. The Doctor concurs and they decide to land instead at an experimental station some way outside the city. There, Vyon has a friend he thinks will help them.

In the HQ of Space Security, Chen is working already on his cover story. The Guardian of the Solar System himself has come here to confer with his number two man, Karlton. The cover story has already been constructed and Agent Lizan brings the information requested by the Guardian, quite in awe of his presence here. She has always been a great admirer of his. She has been assigned to uncover any recent activity on or near the planet Kembel. Her research has uncovered the missions of both Marc Cory and Brett Vyon. Her task was to uncover a traitor, and she has done so. She shows Chen an identity profile on Vyon. Born on Mars -- Colony 16 -- joined space Security in 3990. Two promotions - 3995 and 3998. His photo is included. Chen seems unusually concerned that the information is accurate. There must be no mistake as this man will be branded a traitor and will be hunted down. Lizan assures him that the computerized information on all 40 billion people in the solar system is accurate and separate. There is no scope for error. Convinced, Chen has the data sent out to all stations. Gantry's data will be along shortly.

Chen is pleased. He is certain that Cory is dead on Kembel and believes that Vyon and Gantry are the people who stole his ship. However, he is also convinced that they weren't working alone. There may be other beings with them from other galaxies who helped them steal the Spar. All agents are to be recalled to Earth to hunt down the group. If they reach the landing zone before this is done, all of Central City will be cordoned off until they are found. The fugitives are to be killed on sight. Lizan leaves to post this information.

Chen expresses appreciation for Karlton's efforts. However, he is distressed that two missions went to Kembel without the knowledge of the head of Space Security. Karlton assures him that all missions in the future will be cleared with him, but for Chen this is too little too late. Karlton protests, saying that Cory's mission was undertaken without any sanction at all and that Vyon could hardly be stopped from mounting a rescue mission after Cory's distress call. Chen listens quietly to this. Then his only comment is that he must do better than that; he would hate to have to lose Karlton.

The Spar ship approaches the research station landing pad. Vyon is concerned that there is insufficient power for a soft touchdown, but the Doctor has faith. They must do everything in their power to keep hold of the taranium and to warn someone in authority.

While awaiting the Spar's return to Earth, Chen muses over the future with Karlton. Once he recovers the taranium, he will have even greater standing with the Dalek alliance. He wants the number 2 position next to the Daleks and he will have it. Karlton wonders whether Trantis, as leader of the largest galaxy, wouldn't be the more obvious choice for this position. This causes Chen to react angrily. The Daleks don't like or trust Trantis. And even if this is so, he himself has a plan to put Trantis out of the way for good. Then he shall be next in line. And, Karlton reminds Chen, he will be right behind him.

Chen asks who is in command of the agents tracking down Vyon and Gantry. Karlton tells him of the agent called Kingdom - hard, ruthless, efficient, loyal. The perfect choice. A call comes through and Karlton takes it. The "traitors" have arrived, but not in the city. They have crashlanded at the experimental station. Chen is pleased. They will be much easier to find there.

The Doctor, Steven, and Vyon emerge from the Spar. The landing was rough but not a true crash. They and the taranium are all in one piece. They head for the office of Vyon's friend, Daxtar, unaware that they are being observed.

Agent Sara Kingdom, cool and in control, enters Karlton's office for a quick briefing. She is not surprised at all to see the Guardian of the Solar System waiting for her. She is all that Karlton said she was. She has already been briefed on the surveillance information from the research station -- Vyon and two humanoids are loose in the main block of the station. She is heading there personally to capture them herself. But first, Chen says, there is something he must tell her...

At the station, the Doctor and Steven are becoming increasingly impatient. Daxtar, Vyon's friend, still has not met them and they are sitting ducks here. By now, the ship has been detected and hundreds of people are likely looking for them right now. On top of that, the station appears deserted. This could easily be a trap. Vyon is still convinced they must wait as Daxtar is the only person who will believe them. At that moment, Daxtar arrives, impatient to hear their story.

Chen finishes his explanation of the taranium which Vyon and the others stole from him. Kingdom assures the Guardian that she will take the utmost care to retrieve it unharmed. Then she will kill the traitors. Chen dismisses her and she is off. Karlton congratulates Chen on the story he fabricated, omitting all mention of the Daleks and their alliance, and he is sure Kingdom bought it completely. Of course, says Chen, it is easy for a soldier like her to accept a story about waging war for a "peaceful end". He has no doubt that she will succeed.

Daxtar listens to the story, barely maintaining his belief. The Guardian of the Solar System in league with the Daleks to take over the universe is almost too much for him to bear. But he appears to believe it when all is said and done. The Doctor wishes to leave the next phase up to Vyon and Daxtar while he and Steven return to Kembel to "recover something" they left behind. Daxtar thinks he is speaking of the taranium and is astonished to think they might have left it on Kembel. However, the Doctor realizes Daxtar is in on the conspiracy with Chen - he never mentioned anything to Daxtar about the composition of the core. The only way he could have known that it was taranium - and been so concerned about it - is if he knew from the start what it was and what is was for. Daxtar tries to respond, to cover his tracks, but is not very convincing. He appeals to Vyon, his oldest friend, but he has already implicated himself and Vyon already has his gun in his hand. With cool efficiency, Vyon shoots down his old friend.

The Doctor denounces Vyon as an idiot. He had no call to take that man's life, no matter his crime. There is always another way and now they will never get any information from Daxtar. They must know who they can trust!

Back on Kembel, the Daleks receive a report from Chen, detailing the arrival of the fugitives. The core is nearly back in Chen's hands, although it has not yet been recovered. Chen also states that the fugitives come from the 10th galaxy, Trantis' domain. Standing nearby, Trantis hears this and reacts with an angry denial. This is a trick by Chen, jealous of Trantis' power in the alliance, to discredit him. Without confirmation, the Daleks refuse to act, but they assure Trantis that once the fugitives have been caught and killed, the truth will be discovered. He had better hope Chen is wrong.

Vyon decides to try and get to the security building himself and send out a message regarding the Dalek plot. The Doctor is extremely sceptical of this plan. One "friend" has betrayed them already. Who knows how many more are waiting for them. But with no other option available, the Doctor agrees to try this but has little hope for its success. He is proven right when a heavily-armed Sara Kingdom enters the office. Vyon is overjoyed, seeming to place great value and trust in Sara. However, she levels her gun and demands the taranium. Vyon is crestfallen to think that she is part of the conspiracy.

Vyon launches himself at Kingdom unexpectedly, wrenching her off balance. He shouts to the others to run and they do so. Vyon wrestles with Kingdom but the fight seems to have gone out of him. He is easily defeated and Kingdom shoots him down without hesitation. She then heads off after the others, shouting to her partner, Borkar, to join her.

The Doctor and Steven become aware as they hare down a corridor that Vyon is not following them. They must find someplace to hide and wait. The Doctor points to the nearest doorway and they go inside. They are planning to simply wait at the door, but the room draws their interest. It is large and very high, but there is no furniture in it. It looks more like a gymnasium or an operating theatre. In the centre is a pedestal with a strange plastic cage on top. There are aerials on top - probably transmitting equipment - and mice inside. As Steven returns to the door, the Doctor surmises it might be part of some experiment.

Nearby, two scientists, Froyn and Rhynmal, are indeed preparing an experiment. Froyn is concerned that pressure counts have risen prior to the experiment, but Rhynmal is anxious to proceed as all continuum readings are at optimal levels. They are unaware of the Doctor and Steven. Borkar, now joined by his boss Karlton, enter the control room looking for the fugitives. Rhynmal's response is short and to the point -- get out and don't interrupt. Not even Karlton's rank holds any sway. The experiment is ready and no one will stop them. Froyn reports the pressure count is back to normal and Borkar and Karlton leave in a huff. The two single-minded scientists get back to their work, starting the "dissemination countdown" at 10 seconds.

Steven thinks he hears someone coming. He assumes it is Vyon, but it is Sara Kingdom. She bursts in, gun drawn, and orders them to hand over the taranium. Outside, Karlton hears this and fetches Borkar to help. The Doctor starts to protest but is stopped when a massive surge of energy washes through the room. All three of them grimace in pain as their bodies are bombarded with the powerful waves. They feel as if their bodies are being torn apart.

Outside, Borkar and Karlton pound on the door. It will not open while the experiment is in progress. They can only guess what is happening to Kingdom, the fugitives, and the all-important taranium.

Froyn and Rhynmal track "dissemination" and "projection" readings. A slight power loss is adjusted for. After a moment, computer control is cut in and the experiment is over. They have achieved perfect dissemination. But Froyn is concerned when he registers the door to the dissemination chamber opening. Both men race from the control room. They find Borkar and Karlton in the experiment room and are horrified that their presence may have affected the experiment. The Space Security people are more concerned that the fugitives were in the room. Now they are gone. The scientists tell them that this was a molecular dissemination experiment and, from the looks of it, it went perfectly. But where, then, are those three people?

They are, at this moment, being hurled through space in a molecular form. Karlton, asking for the impossible, orders them brought back. The scientists are not certain there were people in the room at the time, and even if there were they cannot be brought back. The entire point of the experiment was to send the mice through space by matter transmission. They are headed right now toward a strange planet in a distant galaxy, then nature of which is unknown.

The nature of the planet is very similar to that of Desperus - damp, swampy, and coated in a layer of fog. There is less tall vegetation - mainly scrub - but it is thick and omnipresent. It is here that Steven, the Doctor, and Sara Kingdom arrive. They appear to be in one piece, but all are unconscious.

Meanwhile, the Dalek Supreme is getting impatient for a report from Chen. There has been no further contact with him since his previous message, saying the core was nearly in his possession. He orders a Dalek to contact him again for an update.

Back in the control room, Karlton oversees the work of the scientists, badgering them with impatient questions. It will take them some time to know whether the mice - or anything else - reached the planet Mira. Mira was chosen because of its distance, as shorter-range experiments have already proved successful. There is no way to tell if the people caught up in the experiment will survive. Cellular fragmentation has never been tried on humans. Karlton asks why the experiment was not halted when Space Security entered, but he is told it was too late to stop at that point. He turns on Borkar, blaming him for not forcing the scientists to stop, even though he himself was there at the time. He marches out, ordering Rhynmal to inform him when they are certain the transmitter cage has reached Mira. Praying that the experiment succeeded and that Karlton's fugitives are safe on Mira, Froyn and Rhynmal scan for any sign at all. Shortly, they receive it. The transmitter at least has arrived. They breathe a sigh of relief.

On Mira, not only is the transmitter in one piece, but the mice are alive as well. This information is being sent back to the scientists on Earth.

Later, Karlton reports this fact to a worried Mavic Chen. He knows that this proves nothing - the fugitives and the taranium could still be scattered in a billion fragments all over the universe. The latest message from the Daleks has him rattled. The Daleks could just as easily invade Earth and destroy it by force to punish him for failure. But Karlton calms Chen down by proposing an idea. He can tell the Daleks that he trapped the fugitives in the cellular projector on purpose and sent them to Mira - which is not far from Kembel as it happens - so that the Daleks could collect the taranium themselves. This was also to divert unwelcome attention to the fugitives. Chen warms quickly to this plan, sure that it will prove his loyalty to the Daleks and their plans. But he is concerned that the taranium may have been destroyed in the projector. Karlton diverts this fear by playing to Chen's ego. This brings the maniacal Chen round - in fact he begins a deluded rant about being #2 next to the Daleks in the alliance. He will be one step away from the very highest position in the universe, which is his ultimate goal. Karlton knows he will be #2 behind Chen, but his undertone makes it clear that he has higher ambitions himself.

The Doctor is the first to wake, quickly checking himself over for any broken bones or misplaced parts before standing up. The place seems familiar to him, but he cannot identify it. Not far away, Sara lies still, unconscious. However, first one arm and then the other rises and falls limply. It is as if they are being picked up by an unseen hand.

A moment later, Steven awakes, very near to Sara. He checks on her, finding her alive but still very much unconscious.

The Doctor examines the transmitter cage for a moment and then decides to find Steven. He is sidetracked when he sees clawed footprints appear in the damp ground as if by magic. It is as if something large and invisible were walking around the swamp. The Doctor finds Steven with Sara. Steven is at a loss to figure out what happened, but he has kept his wits about him enough to disarm the woman before she wakes up.

As she stirs, the Doctor begins badgering her to answer questions. Unarmed, she must do as he says. Steven goes off to find a more secure hiding place while the Doctor helps Sara up. She is still belligerent toward the "traitors". The Doctor spits back that she's lucky to be alive and this seems to sink in. Perhaps he's not what she was led to believe.

On Kembel, the Dalek Supreme has not wasted any time in acting on Chen's message. A pursuit ship has already landed on Mira. The Daleks aboard report they have found strong life sign readings, but have not made contact with the fugitives yet. It is only a matter of time.

It is Sara's turn for questions and she is anxious to know where they are and how they got here. While the Doctor cannot answer the first, he can answer the second. He explains cellular dissemination and how their bodies were broken up, transported, and reassembled here. Steven and Sara are shocked but have no choice but to believe him. Steven asks about the mice and the Doctor has an answer for that as well - the cage contains a transmitter. Chen will know where they are, and therefore the Daleks will too. No doubt they will arrive to hunt for them very soon.

In fact, the Daleks have already found the transmitter. The mice are strange to them but non-threatening. However, the transmitter is sending signals to Earth. It may even give away their presence on Mira. They destroy the cage - mice and transmitter included - for their own protection. There are still strong life readings in close proximity, but there is no visual contact. Using their perceptors, the Daleks pinpoint the reading and fire full power. There is a roar from the darkness, but no creature. It is soon clear that there are invisible beings here. The search must continue, but they must watch their perceptors carefully and scan for the invisible creatures.

Back on Earth, Froyn and Rhynmal have noted the loss of signal. They worry about the setback in their experiment, but Karlton knows that it likely means something else. The scientists do not know if there are any intelligent native species on Mira and speculate that the "criminals" might have damaged the transmitter. They suggest sending more mice and another transmitter but Karlton forbids it. He orders them to keep trying to regain contact and to keep him informed.

On Mira, the Doctor scouts round for any sign of the Daleks. He hears instead the sound of large heavy footsteps and raspy breathing. He is attacked by an unseen force and barely manages to beat off the invisible creature with his walking stick. Now he knows what this place is -- the planet Mira. The invisible creatures are dangerous predators called Visians.

Nearby, Steven is trying to tell their true story to Sara. He concludes by telling her that Brett Vyon - the man that she callously murdered - was the only one who could have warned Earth about the Daleks. But she does not believe him. They are all traitors to the solar system; they stole the taranium which was desperately needed to help spread the peace of the solar system throughout the galaxy. She admits she doesn't know how it was to help accomplish this, but she doesn't care. She repeats adamantly that she was following her orders. Steven reacts angrily, asking her why she didn't even bother to ask any questions - of Chen or of Vyon. She simply obeyed Chen and killed a supposed "traitor" -- one of her own people -- without asking a single question! Faced with Steven's anger, Sara's own seems to subside suddenly, to be replaced by something else. Is it dread? She tells him his story simply mustn't be true. She is almost begging. The Doctor returns and tells her most convincingly that it is true. It is clear that she believes him...and hates herself for her actions. Because, she says, Brett Vyon was her brother.

Filled with anger and sadness, Sara moves away from the others to be by herself. The Doctor stops Steven from going after her. This explains why Vyon was so quick to trust her and equally quick to lose his will to fight when he thought she was in on the conspiracy. There is nothing they can do for her grief now. However, Sara is quickly back with them. Something brushed against her out there, but she could see nothing. The Doctor explains about the Visians. They may even pose a more immediate threat than the Daleks. They must try to leave this planet right away, but the Doctor admits he doesn't know how.

The group tries to move off to some safer location, but see the undergrowth moving ahead of them of its own accord. They are surrounded by Visians.

Karlton is sure that the Daleks have already reached Mira and Chen knows this means he must return to Kembel immediately. The Daleks must believe his story, but there is always the possibility that the taranium will not be recovered. In that case, Chen orders Karlton to prepare "his party". At a word from Chen, they should head for Venus where they can hide. If the Daleks mistrust Chen and invade the solar system without him, Karlton's force should be able to ambush and destroy them. And then Kembel. It will mean mastery of only this galaxy, but that is a start. And it is certainly better than subjugation to the Daleks.

The Daleks order the Doctor to hand over the taranium core, but the Doctor wants an assurance that he and his friends will not be killed. The Daleks will obviously not give him such an assurance and when their detectors indicate the Doctor holds the taranium, their orders grow more insistent. But the Doctor realizes they dare not fire directly at him for fear of damaging the core. And this delay is all they need. The Visians attack the area in force, concentrating on the Daleks as the most immediate threat. The Daleks break formation and begin firing wildly. In the chaos, the Doctor, Steven, and Sara run for their lives.

However, the Visians are large, slow-moving creatures, no match for even indiscriminant Dalek fire. Soon the attack is over, the Visians either dead or running. The Daleks return to searching for the fugitives.

The Dalek Supreme receives this news and is not pleased. He refuses to send reinforcements to Mira, certain that the force already there is sufficient enough for this relatively simple task. He orders them to redouble their efforts, warning them that failure will not be tolerated.

The Doctor has made for the only logical destination, the Dalek ship. He and the others have made a quick observation of it from their hiding place and have formulated a plan. There appears to be only one guard, so getting aboard should be easy. The Doctor heads off to be the distraction while Steven and Sara wait for their cue. Sara is worried as she's certain the other Daleks will return any moment, but Steven trusts the Doctor. And he tells her she should learn to do the same. He's beaten the Daleks before and he knows what he's doing. Like it or not, she knows she has no choice.

Boldly, the Doctor approaches the lone Dalek guard, telling it he has brought the taranium. He says he's realized he cannot beat the Daleks and has decided to give himself up. However, he asks the Dalek to help him and his friends escape the planet in exchange for the core. The Dalek is concerned about the others and where they might be, but the Doctor says they will stay hidden until a deal is concluded. He produces the taranium to draw the Dalek's attention away from the fact that Steven and Sara are creeping up behind the creature at this very moment. It works. The Dalek is distracted long enough to allow the other two to cover its eye stalk and blind it. The Doctor joins the battle just as the Dalek begins to fire wildly, spinning around and calling out. The Doctor and his friends are able to avoid the deadly rays and to direct the Dalek's spin away from the ship's entrance ramp. They hurry aboard and seal the door. The Dalek guard nearly shoots the returning patrol.

The Doctor begins the launch sequence but the power buildup is very slow. Steven and Sara work to speed it up. Outside, the Daleks assume attack formation. The engine whine rises in pitch but there is nothing the Doctor can do to boost it further. He can see through a window that the Daleks are ready to attack. All of them together will be able to stop the ship's takeoff. But the Doctor and the others succeed. The ship takes off before the Daleks can fire a shot. The take off is bumpy and rapid.

Meanwhile, Mavic Chen has returned to Kembel. The Dalek Supreme is quick to accuse him of failing to retrieve the core. But, bolstered by Karlton's cover story, Chen refuses to accept the charge of incompetence, nor the threat of punishment carried with it. He sent the fugitives and the taranium to Mira so the Daleks could recover it quickly and secretly. This also saved their plan from discovery, as the fugitives could have contacted someone on Earth who could have stopped the Daleks. Emboldened, he actually blames the whole situation on the Daleks' own lax security. If they had stopped the core leaving Kembel in the first place, none of his actions would have been necessary. Aware that this was the same argument Zephon used prior to his extermination, Chen waits for the reaction. But there is none this time. The Dalek supreme does not respond at all, instead turning his attention to events on Mira. He learns that the fugitives have escaped in the Daleks' own pursuit ship, leaving the patrol stranded and under constant attack from the Visians. Barely able to contain himself, the Dalek Supreme despatches a rescue ship to Mira, promising to deal with the patrol's failure on their return. He himself will now supervise recovery of the taranium personally. Chen takes great delight in gloating over this true demonstration of incompetence. He is sure he's off the hook now. He taunts the Dalek Supreme, but not enough to merit a rebuke. Instead, the Dalek Supreme vows to recapture the fugitives and retrieve the core.

On board the Dalek ship, the Doctor, Steven, and Sara have worked out how to fly the ship and are on course for Earth. The Doctor's mind has moved on to another problem. He has decided to try and make a copy of the taranium core - so exact that it will fool the Daleks. They can turn it over and escape with their lives. Steven is worried that it cannot be done, but Sara has learned much about the Doctor in a short time and now has complete faith in him. Suddenly, all three of them notice a change in the ship's course. The Doctor scans the instruments and realizes they are headed - thanks again to Dalek remote control - toward Kembel. Steven quickly locates the remote relay on the control panel and yanks it loose from its connections. There are sparks and smoke but it does the trick. The ship returns to its original course. Sara is quite put out by Steven's abrupt and heavy-handed actions. She thinks him a barbarian, but Steven assures her that while he may be a few centuries behind her in technological know-how, there are still some things he can handle on his own. While the Doctor seems to agree with him, he does go off with Sara alone to work on their copy of the core.

The Dalek Supreme does not give up so easily. Detecting the failure of the remote control, he then activates a magnetised beam to lock on and drag the ship here to Kembel. Chen looks on innocently, needling the Dalek Supreme about the possibility of his own "failure". The Dalek Supreme can barely suppress the urge to destroy Chen, but says only that the Daleks will win, the fugitives will be destroyed, and the core will be recovered.

The Doctor and Sara have soon completed their copy of the core. It was easier than they expected and the Doctor is pleased with the results. There is, however, the difficulty of charging the copy. Otherwise, the Daleks' perceptors will sense immediately that the core is a fake. They set about this task, unsure how to do it. Steven joins them, impressed by the copy. He suggests charging it using the gravity force from the ship's power centre, but the Doctor dismisses the plan as too primitive and too dangerous. Sara takes the criticism one step further. Even though Steven is sure it would work, Sara likens the idea to the primitive "science" of ancient Rome. It worked too, but is antiquated and worthless now. Stung, Steven becomes more resolved to show them it could work.

Sara and the Doctor are distracted again by the course readout, which now registers that they are being dragged toward Kembel - and the Daleks. The Doctor works out that magnetisation is behind it and she and Sara move off to try and find some way to neutralise the beam. Steven, left behind with the fake core, takes matters into his own hands and taps into the g-force of the ship. He connects the core, but the force is unstable and overwhelming, leaping into him and hurling him to the floor with a scream. The Doctor and Sara come running. The Doctor is glad to find that Steven is still alive and breathing, but quite unconscious. Sara is furious at Steven for meddling but is shocked to find that the fake core has been properly charged. It now reads just like the real one. The Doctor, too, is pleased with this. He sets about trying to revive Steven.

On Kembel, the Dalek Supreme monitors the descent of the captured pursuit ship. It has entered the atmosphere and is being slowed down for a soft landing. Again, Chen is impressed with the efficiency of the operation. However, he doesn't think the fugitives should be killed immediately. He suggests instead that they be taken to Earth for trial and execution as traitors to the solar system. This would put a plausible end to the story that he has told regarding the fugitives. If they were to simply "disappear" on Kembel, someone from Earth could get suspicious and start asking questions. But the Dalek Supreme refuses to listen to this, whatever Chen's ulterior motive may be. As a member of the galactic alliance, it is Chen's duty to either forestall the questions or put off the questioners until the Daleks have conquered the solar system. Then it will be too late for questions. Once the taranium is back in Dalek possession, there will be only a short time until victory. Unable to refute this, Chen agrees. The Daleks will decide the fate of the fugitives. Chen and the Dalek Supreme head out to meet the ship at its landing point.

The Doctor calculates 5 more minutes until they land. He turns his attention back to Steven. The boy is conscious and increasingly mobile, but he cannot speak. He is surrounded by the gravity force field. It will not harm him any further, but the Doctor has no way to reverse its effects. However, as his mind works on the problem of what to do next, Steven's condition gives the Doctor an idea.

Soon the ship is landing. Chen and the Dalek Supreme watch it come down, confident that the delay in their plans is finally over. Inside the ship, the Doctor knows it is time to face the Daleks. He gives the fake taranium to Steven, who moves zombie-like on the Doctor's instructions. Sara is very sceptical about the wisdom of this plan, but the Doctor tries to be as confident as possible. He reminds her to let him do all the talking once they get outside.

The three fugitives emerge from the Dalek ship, Steven in the lead. Chen is quick to spot the taranium and orders its return. But the Doctor refuses to hand it over, knowing that the Daleks will not fire for fear of damaging the core. The Doctor announces he will only hand over the core outside his own ship, the TARDIS. At first, the Daleks balk, but the Doctors stands firm. The Dalek Supreme eventually agrees and the Doctor leads his party down the ramp. Chen calls to Sara and she responds by calling him a traitor. Chen's fear has been realised - she knows the truth and has sided with these other two. The Doctor and his friends move toward the TARDIS, Steven bringing up the rear to hold off the Daleks' fire.

They reach the TARDIS in a short time and the Doctor sends Sara to open the door. He instructs Chen that Steven will hand over the core once he and Sara are safely inside. Chen thinks this shows cowardice and self-preservation on the Doctor's part, but the Doctor obviously is working to a plan. From inside the ship, the Doctor instructs Steven to hand the core to Chen and then enter the TARDIS. Still zombie-like, Steven hears the instructions as if through water, distant and distorted. But he does as he's instructed, still moving quite slowly. Chen is triumphant when he holds the core, unaware that it is fake. The Dalek Supreme wastes no time in ordering his Daleks to fire on Steven as he slowly retreats. The blasts hit him squarely in the back and propel him into the TARDIS. But he is unharmed. The doors close and the ship dematerializes.

The Dalek Supreme is stunned at Steven's survival. All of the weapons were operated at full power and no human can withstand that. This concerns him greatly, but Chen does not seem to care. He holds the "taranium core" aloft and rejoices. The invasion can now go ahead and soon the universe will be theirs!

On board the TARDIS, Steven has completely recovered from his ordeal. The Doctor surmises that the Dalek guns destroyed the gravity force field around him. He was lucky they didn't fire a second time. Steven, emboldened by his success, suggests trying to recreate the accident in order to gain the permanent protection of the force field. He's sure he can do it, but the Doctor rebukes him sternly. His actions were rash and dangerous and stupid. He could have destroyed the spaceship and killed them all. But Steven persists, further provoking the Doctor. There will be no more of these dangerous experiments and that is final. He is the leader and what he says goes. And if Steven doesn't like it, he can get off the ship. Firmly chastened, Steven agrees to forget the gravity experiment idea.

The TARDIS has in fact landed on Earth. It is Liverpool, 1965, and the "poisonous atmosphere" the Doctor detected is simple pollution. The ship's police box exterior causes some consternation for a police sergeant when he emerges from his station. He spots the police box where it sits at the end of the yard. It certainly shouldn't be there, and it is just one more headache on an already busy day. Decorations adorn the station house - greenery and bunting - and the strains of a somewhat warbly carol reaches him from the lane. It is Christmas Day. Two PC's arrive in their car and walk up the lane, lamenting the fact that they have to work on Christmas. Their Sergeant is quick to draw their attention to the police box. He has no idea why it is there and does not appreciate the wisecracking "answers" his men provide him. He orders the two hapless PC's to stay outside and watch over the box, much to their chagrin. They wonder if the Sergeant is afraid it's going to fly away.

Inside the TARDIS, the Doctor is making ready to go outside and fix the scanner. Steven protests, wondering why it's OK for him to go out and not them. The Doctor explains tetchily that where Steven and Sara come from, the Earth's air is pure. The pollution outside is the worst he's run into in years - it would be very dangerous for them. As he is used to all sorts of atmospheres, he will be fine. Sara wonders what to do if something happens to him. He tells them to wait - the repairs should only take a few minutes - and if he doesn't return after a reasonable time, then and only then can they come outside. The protective Steven is not too pleased with this arrangement, noting that without the scanner they cannot know what is happening to him. But the Doctor silences him and orders him to open the doors.

However, the Doctor only manages to peer out the door for a second before going immediately back inside. He has come face to face with one of the policemen standing close by. The policeman is stunned by this and tries to tell his partner there's a bloke inside the police box. But when a test of the doors reveals them to be firmly locked, he is hard pressed to believe the story.

The Doctor's brief look outside has told him at least this much -- they are on Earth at a police station. Sara wonders if the Doctor is glad to be back home, but learns quickly that Earth is not his home at all, despite the outward appearance of the TARDIS. He has also realized that the pollution outside is not as hazardous as he first thought. He will go back outside and distract the policemen guarding the TARDIS. After a few minutes, Steven can come out and fix the scanner. Steven gives a smart salute and does what he is told.

The Doctor goes outside and is immediately taken into custody by the two policemen. Obviously their Sergeant was right to have them here.

Inside the stationhouse, the Sergeant completes one report only to have the next Christmas kook right on his heels. He's an old man in a mackintosh who refuses to give his name. His complaint -- "They" keep moving his greenhouse. And he blames it on "the revels". Before he can ask any questions, though, the Doctor is brought through by his men. They are taking him to CID. The Doctor stops at the sight of the man in the mackintosh, sure he has seen his face somewhere before. He finally places it - the marketplace at Jaffa! Both the Sergeant and the man are taken aback at this. The Doctor is just another nutter, they figure. The constables take the Doctor into the Inspector's office quickly.

Meanwhile, Steven has followed the Doctor's instructions and waited before leaving the ship. He emerges but is immediately forced to hide behind the nearby police car when a constable emerges from the station.

Jumping to the obvious conclusion, the Inspector thinks the Doctor was living in the police box due to the housing shortage hereabouts. Not the nicest way to spend Christmas. The Inspector is surprised when the Doctor claims not to have known it was Christmas as he travels about too much on a quest for knowledge. The Inspector then tries to determine the Doctor's nationality, running through English, Scottish, Irish and Welsh. The Doctor volunteers helpfully that he is "a citizen of the universe, and a gentleman to boot". It will clearly take all of the Inspector's patience to deal with his caseload today.

Coming out of hiding once the coast is clear, Steven notices a policeman's jacket in the back seat of the car. Boldly he snatches it. It does not fit well but he feels certain it will help him blend in.

In the station, the Sergeant listens with growing impatience to the strange man's tale of his errant greenhouse and its multiple moves. Through the window he spies Steven in his "uniform" and is quick to go out and drag him inside, mistaking him for the "new man from G Division" come to give them some relief. Seeing an opportunity, Steven plays along, saying he's come about "the old man". He's in a hurry to find the Doctor, but the Sergeant won't interrupt the Inspector and makes Steven wait in a chair. Then it's back to the man in the mac, who gravely reports that his greenhouse is definitely not in his garden where it belongs. His look and his tone challenge the Sergeant to do something about this appalling situation.

And things are no better for the Inspector either. The Doctor is trying to explain to him that the "police box" is really a machine for travelling in space and time and that it belongs to him. The Inspector utters a long sigh but can find no words to express himself. The two constables, however, know exactly the right word -- nutter! The Doctor challenges them, trying to ascertain the meaning of this word, which only convinces the officers more that he's off his rocker. The Inspector, worried about the possibility of an army of deranged gypsies camped out in the police box on their doorstep, sends the officers out to check the box again.

Before they get outside, Sara emerges from the TARDIS. She sees no one about and so brings out a small folding ladder in order to reach the scanner eye, the smartest person in the TARDIS crew so far. But just as she sets it up out of sight round the back, the constables leave the station. They are pleased at the sight of the attractive young woman before them. It does not occur to them that she could have anything to do with the crazy old man in CID, even though she is hanging around the police box. They assume she must be headed to a fancy dress party due to her strange clothes and urge her to be on her way. There's a lot of cranks hereabouts at Christmas, they tell her, and she won't want to get mixed up with them. Sara tries to protest - that she's not going to any party and that she must fix the scanner eye - but all to no avail. Urged on by the policemen, she goes off round the corner, furious at the Doctor and Steven for getting caught up in all this trouble. She watches as the policemen turn away, listening to the Christmas carols drifting in from the lane. As soon as their backs are turned, she makes for the far side of the ship, determined to complete her task.

Inside the station, Steven paces nervously. The Sergeant tries to get him to sit down and be still, but Steven won't sit. At least the man in the mac has gone away for the moment. When the Doctor and the Inspector emerge from the CID office, Steven leaps to the Doctor's side. It is clear to all that these two know each other, but Steven's disguise as a policeman from G Division holds. Steven confirms that the Doctor is "a nutter" and that G Division is well acquainted with him. Both the Sergeant and the Inspector are glad to be rid of him. They can't urge Steven strongly enough to take him away. The two head outside as quick as they can with a great show of bluster.

However, they emerge to see the two constables pulling Sara down off her ladder next to the TARDIS. Neither of them can figure out what is so attractive about an ordinary police box. Steven tries to take charge of the situation, saying he knows Sara as well and that she is an "accomplice" of the old man. The conversation drags and Sara becomes impatient. She throws an elbow at her captors and races back to the TARDIS, determined to make an end of this idiotic delay. Steven and the Doctor follow her quickly and slam the door shut. The ship dematerialises a moment later.

The constables are thunderstruck. When the Sergeant comes outside a moment later, he sees what has happened and decides - wisely - not to recall that there was ever a police box there in the first place!

Inside the ship, Steven explains how he found the policeman's jacket and managed to pass as one of the police. The Doctor says he enjoyed himself perplexing the Inspector. Both of them seem to have forgotten the damaged scanner, which Sara reports that she fixed with no help from either of them. But she hasn't obviously had time to test it yet. The Doctor seems less concerned about the scanner than the taranium. He reminds his companions they cannot forget about the Daleks. They too have time machines and will follow the TARDIS soon. He thinks it unlikely they have discovered the fake taranium yet, though, and they won't invade the solar system until they've tested their time destructor and made certain it works. The Doctor still has some time to defeat them. He starts to formulate a plan to destroy the real taranium, but doesn't get far before Sara notices the time rotor slowing down. They've landed again. The atmosphere here is much improved from the last landing place. Activating the now-functioning scanner, they see a young girl in what appears to be an old-time sawmill. A man in black with a long thin moustache is lashing her to a plank about to be sawed. She screams at the top of her lungs, startling all the travellers.

Acting quickly, Steven opens the TARDIS doors and races out, Sara and the Doctor right behind him. Steven attacks the man in black, knocking him easily to the floor, while Sara and the Doctor free the girl. However, she doesn't seem glad to see them at all. She immediately sits up and starts whining about how they've "ruined everything". The travellers hear a very annoyed male voice shout, "Cut!" He is clearly very angry as he comes into "the mill". It is actually a film set in old-time Hollywood and the director, Steinberger P. Green, is angry at the "bums" who've ruined his shoot. He tells his minions to summon the studio police to remove these crashers. Green and his camera crew advance on the travellers, blocking their path to the TARDIS. With nothing else for it, Sara and Steven engage in a fight with the men. They are badly outnumbered but their skills are far superior, especially Sara's. Green stands back and watches in awe as they beat up virtually the entire crew then barrel through the rest and head out a door. The Doctor reluctantly follows. Chaos breaks out with actors, technicians and Green himself shouting after the set crashers.

Sara is in the lead and races toward the next set of doors, leaving Steven and the Doctor far behind. The two men, chased by the remaining crew members not beaten senseless, take another turning into the depths of the what is clearly the wardrobe room of a very large film studio.

Sara emerges without her friends on another set, this one dressed like the palace of a sheikh. From backstage she sees "the sheikh" himself sweep somewhat grandly into the room to address a scantily-clad female lounging on a chaise, vowing to sweep her away across the desert. However, he is stopped mid-sentence by the director, a Scandinavian called Ingmar Knopf who decries "the sheikh's" performance as terrible and without passion. Soon the posh German leading lady is joining the criticism of the poor "sheikh", in truth an Englishman who thinks all the badmouthing is quite unfair.

Sara watches from hiding as the previous director, Green, arrives on the set with some of the technicians she beat up. Knopf is outraged at the interruption and barely listens as Green asks about the three people who beat up his camera crew. Far from being upset, Green seems almost desperate to find them - to hire them for his film! But Knopf will not listen to the man as he has problems of his own. He is waiting for a Professor Webster to arrive to advise on the set. As Green goes, Knopf spots Sara emerging from hiding. He thinks she is an extra for the harem and wants her costumed accordingly!

Elsewhere in the studio, Steven and the Doctor have managed to lose their pursuers. They take a moment to catch their breath and then decide to try and find Sara. The Doctor is sure he knows which way she went and orders Steven to stay put in the wardrobe room for a moment while he moves off to find her. However, as soon as the Doctor is out of sight, Steven in approached by two men with clipboards. He thinks at first they are studio police, but soon finds out they are much worse and even more persistent directors' assistants. With his policeman's jacket, they easily mistake Steven for an errant extra and manhandle him away to yet another set. He is late and the cast and crew are waiting. Steven tries to get away, but the two men are very persistent indeed. They shove him forward as he calls out helplessly for the Doctor.

Steven is pushed onto the set without benefit of further costume or makeup. With his policeman's jacket, he looks the part in the Keystone Kops-like film being made here. Unable to leave right away, he follows onto the set with the other extras and does a short car chase bit. But as soon as it's done, he makes quietly for the nearest exit. One of the assistants sees him go, fretting that they'll have to go after him again for a retake.

Back on the Arabian palace set, the actor playing the sheikh rehearses his lines repeatedly, trying to get the passion everyone else feels is missing, although he can't see it. Knopf stops him in order to try for another take, allowing his leading lady another chance to chide his poor acting skills. Into this comes the Doctor, looking for his friends. Seeing the old man's extravagant dress and haughty manner, Knopf immediately mistakes him for Professor Webster, the expert on Arabian history that he has been waiting for. He asks the Doctor for advice on this scene. His only contribution is to tell the leading lady to go and put on some more clothes! This causes chaos to erupt once again, everyone talking at once. The Doctor raps on a nearby trunk to get the director's attention and to everyone's surprise, Sara emerges. The Doctor grabs her and runs off before she can be press-ganged into the film.

The Doctor and Sara leave the set and emerge into a quiet corridor. Sara is incensed as she tells the Doctor of the strange little costumer who kept telling her to take her clothes off, having mistaken her for an extra harem girl. That's why she had to hide in the trunk. The Doctor can sympathize, believing this place to be an utter madhouse. Luckily they run into Steven in the corridor, now without his policeman's jacket. They must get back to the TARDIS and out of here.

Back on the sawmill set, Green has returned, but chaos still reigns. The technicians and crew jabber amongst themselves about the beating they received at the hands of the set crashers, and the leading lady, Blossom LeFavre, is pouring out her woes to anyone who'll listen. She fears Green wants to replace her with someone younger and prettier. Someone like Sara. First the villain, actor Darcy Tranton, and then Green himself assure her this is not the case. As soon as she is calmed down, Green calls for quiet in an attempt to mount another take.

However, Steven and Sara are spotted in the background and the chase is on again!

The Doctor is not noticed in the chaos and makes his way to the TARDIS. There he finds a young and somewhat dejected clown leaning against the box. He bends the Doctor's ears about how his career may be over as directors are always looking for the next new thing. He might already be passé. Most frustrating, the Doctor agrees, but he's not really listening, worrying more about his absent friends.

Steven and Sara are chased back onto Knopf's set, infuriating the master director anew. Green and his men follow, further disrupting his art with their search.

Meanwhile, the Doctor continues to listen impatiently to the clown's woes. He has ideas for a number of wonderful gags for his film, but the studio won't allow him to do them as they've all already been done by Chaplin. Most frustrating. He thinks perhaps he will give up clowning and become a singer instead, but he worries that no one will take him seriously with a name like Bing Crosby!

Steven and Sara return to the sawmill set at a dead run, just ahead of their pursuers. They grab the Doctor and dash inside the TARDIS. The ship dematerializes immediately, leaving the entire group thunderstruck. Blossom whines in disgust, Green in agony at his lost stunt people, and the crew in horror at having to mount yet another take of this miserable scene.

At the end of it all, Professor Webster finally arrives.

Whilst the Doctor and his friends have been visiting Earth and celebrating Christmas, the Daleks have been busy on Kembel preparing the time destructor for its first full-scale test. All circuits are now operational and the taranium core - which they still believe to be real - has been fitted.

In an observation room, Galactic Alliance Representatives Celation, Trantis, and Chen await the start of the test. Celation takes great delight in needling Chen about the theft of the core and the relief he must feel now that the Daleks have recovered it. Trantis still blames Chen for the rumour that one of his citizens stole the core in the first place and reiterates that the fugitives were from Earth. But Chen takes this all in his egotistical stride. The Daleks would not have recovered the core without his help and the main instigator of the theft was an old enemy of the Daleks, an alien time traveller who only looks human. The others wish to debate this point further, but Chen is unconcerned. He is more interested in witnessing the first test of the mighty time destructor.

In the control room, the Daleks prepare the last detail of the test - a subject. But the Dalek Supreme has already chosen the subject. The first victim of the time destructor is to be Trantis!

On board the TARDIS, the Doctor and his companions are clustered around one bank of instruments on the console. There is a time ship following them. Steven is certain it is the Daleks, but the Doctor cannot believe they've had enough time to test the time destructor, discover the fake core, and follow the TARDIS. Sara is in favour of returning immediately to Kembel and trying to destroy the Daleks' invasion fleet, but the Doctor will not consider this just yet.

Celation wonders as Trantis is led to the testing room why he was chosen. Chen knows that this is the only true "contribution" Trantis could make to the time destructor and his ego forced him to want to contribute in some way, to befit his high place in the alliance. Chen does not seem sympathetic to his colleague's impending death at all.

The Daleks prepare to begin, making sure that Chen and Celation are watching losely. They must watch and see the power of Dalek technology to temper their ambition. But they are actually unaware of the initial intended effect of the time destructor. Isolated and unheard in the testing room, Trantis sinks to his knees in abject horror. To those observing, he appears to be going insane. Perhaps that is part of the effect of the time destructor. The Daleks, however, know better and when the machine does no damage to Trantis at all, they quickly trace the fault to the taranium core. They confront Chen, accusing him of deceiving them. Managing to stay calm despite the gunsticks aimed at him, he refutes the charge. He insists that he brought them true taranium and that he can only gain by the success of their plan. He has no reason to deceive them or to sabotage the plan. This makes sense to the Daleks and his life is spared.

Chen realizes that the Doctor has deceived them somehow - damaging or switching the core. He had no time to check the core once it was retrieved, so quickly did the Daleks want to begin their tests. They must find the Doctor to find the answers. The Daleks send an urgent request to Skaro for a time machine to be sent to Kembel. In response to his protestations of innocence, Celation is allowed to return to his home planet, but Chen is to remain here. As for Trantis, the Daleks decide to complete what they had planned to do with the time destructor - exterminate him. As this is done, Chen realizes - with very mixed emotions - that he is now the highest-ranking member of the Galactic Alliance. The highest one still alive, that is.

Steven continues to track the ship following the TARDIS. Sara is impatient and cranky, but the Doctor remains calm. When the pursuing ship starts to gain on them, the Doctor decides to confuse it by landing sooner than expected.

Speaking of confusion, the scene is again on the planet Earth, in the broadcast booth of the Oval. England v Australia for the Ashes. Although their voices seem to indicate otherwise, the announcers assure their listeners that this has been quite an exciting match indeed. However, the Australian Scott is not so sure the English batsmen will be able to reach the 78 runs they need to win in the 45 minutes remaining. His partner, Englishman Trevor, is dumbstruck when a police box materialises out of nowhere in the middle of the pitch. Neither of them, despite some hard thought, can ever remember anything like this happening before. Perhaps a look in the record books will turn up some precedent.

Scott is concerned about the time delay. Even if it takes just 10 minutes to remove the box, that leaves just 35 minutes for the English side to make their 78 runs. Trev agrees it is a very bad break indeed for the side. They banter about the weather and then turn to look at the scoreboard. Then, just as suddenly as it came, the police box fades away with "a funny noise". Just under 2 ½ minutes was the length of the delay, a lucky break for England. Back to business, Trev reports they have 42 ½ minutes in which to earn their 78 runs to win. Apparently, nothing can faze a veteran cricket presenter. Absolutely nothing at all.

The Doctor thinks they must have interrupted some sporting event, but Sara doesn't think that looked at all like a proper sport. Steven reports that whatever plan the Doctor had in mind has failed. They are still being followed, and at an ever decreasing distance.

On Kembel, the Dalek time machine arrives. The Dalek Supreme orders a task force assembled for the pursuit and location of the enemy time machine. The Daleks have examined the "core" retrieved from Mira and determined it to be fake. Chen is told that he is to accompany the task force and recover the real taranium core. If he does not succeed, he will be annihilated.

The TARDIS materialises on a rocky, dusty planet, and the travellers peer out the door. Its thin atmosphere is tinged with a hazy glow from its sun. The energy radiating from that sun seems unusually strong. On the horizon, volcanoes dot the landscape. Active volcanoes. This is not a pleasant place at all. They cannot stay long. The pursuing ship has ceased registering. The Doctor realizes this means the other ship has also landed, somewhere out there.

Indeed it has. A rocky outcrop sits alone in the midst of a dusty plain. It looks like the others in the distance, but it is not at all. A door opens in the rock and out steps the Doctor's pursuer - the Meddling Monk! He is still dressed as a monk, habit, skullcap and all. He chuckles to himself happily as he sees that his TARDIS' chameleon circuit has worked perfectly. No one will notice his ship among the outcrops of rock. Then he's off to find his nemesis the Doctor. He has a score to settle.

The Doctor, Steven, and Sara search the area for any sign of their pursuer, Sara complaining all the way. She cannot see the value in going after the Daleks here and she still wants to try to get to Kembel to end all of this. But the Doctor is more and more convinced it is not the Daleks following them at all, and the sooner they face their pursuer, the better. Steven touches a rock outcrop and recoils. It is very hot. The Doctor is not surprised; this is a young planet, still cooling off from its formation. That also accounts for the volcanoes, which continue to erupt in the distance. The Doctor is fascinated by this, but is still troubled by the question of who would take the trouble to pursue the TARDIS and why. He has an idea, far-fetched but still very possible.

Meanwhile, the Monk has had no trouble finding the Doctor's TARDIS, distinctive as it is. He approaches the ship, noting the dusty footprints leading away from it. The Doctor is not inside. Perfect. He produces a small device from his robe and aims it at the ship's lock. He fires and a strange noise erupts from around the TARDIS. There appears to be no damage to the ship, but the Monk seems quite satisfied. He pockets the device and heads off.

But before he can reach his ship, he hears the voice of the Doctor echoing all round him. He congenially asks to talk. The odd atmosphere conducts his voice well. Turns out that the Doctor's hunch was right as the Monk comes into view. Sara draws her gun, ready to shoot, but the Doctor stops her. The two men chat like old friends and the Monk even has a friendly greeting for Steven as well. Sara is, of course, confused.

The Doctor congratulates the Monk on his escape from 1066. The Monk tells him it was a hard job bypassing the dimensional controller, but he managed it. The Doctor laughs him off as an amateur. Steven promises to tell the confused Sara all the details of their previous meeting with the Monk in order to silence her questions. They listen as the Monk admits he followed them with a plan in mind, and that he's already carried it out. He laughs uproariously as he tells them he's stranded them here on the desolate planet Tigus, incredibly pleased with himself. He says he may return some day to rescue them, then he's off toward his TARDIS. Steven starts to charge down the hill after him as the echoing laughter fades, but the Doctor stops him. It is more important now to see what damage the Monk has done to the TARDIS. They hurry off.

Arriving at the ship, the Doctor can tell immediately - despite the absence of any sign of damage - that the TARDIS' force field has been neutralized and that the lock has been broken. They cannot get into the ship! The Doctor fumes as the Monk's laughter - borne faintly by the strange atmosphere, reaches his ears.

Steven tries to physically break open the TARDIS door, but has no success. The Doctor assures him that brute force is not the answer. It will take brain, not brawn to solve this. Thinking hard, the Doctor finds his inspiration literally in the sky. He makes his companions stand back and cover their eyes. He is not certain this idea will work. He judges the position of Tigus' sun, then uses his dark-jewelled ring to focus and reflect the sun's rays onto the TARDIS lock. There is a palpable buzz of energy all round. The ring grows hot in the Doctor's hand. He holds it as long as he can and then is forced to drop it before he is burned. But a strange noise issues from the ship, indicating some reaction. Steven and Sara uncover their eyes to see no apparent change in the exterior of the ship. But the Doctor makes one final adjustment to the lock mechanism and Steven is able to open the door. Steven congratulates him on his genius and all three pile into the ship, the Doctor grabbing up his ring from the ground on the way. They are soon on their way again. But the Monk has crept forward and watched the whole scene from hiding. He has been cheated of victory this time, but his face darkens as he vows to get even. He shouts to the heavens that the Doctor has not heard the last of him. The vow echoes darkly all across the plain.

The Doctor and his friends know that the Monk will be back on their trail as soon as he can get going again, but this time they will be ready for him. Steven asks the Doctor to explain how he broke into the ship, but all he will say is that both the stone in the ring and the rays of that sun have certain "special properties". He refuses to elaborate further despite all the questions, but he does report that the lock mechanism is badly damaged. It will have to be repaired. Steven is again posted at the time curve indicator, looking for any signs of the Monk's renewed pursuit.

On Kembel, the last of the Daleks in the task force are aboard and the countdown to dematerialisation commences. The tracking device has located the enemy ship, about to land on Earth in 1966.

London. New Year's Day, 1966. Just after midnight. The bells of a nearby cathedral ring joyously, sparklers fizzle, and people laugh and chatter as they pass by. For once the TARDIS fits in on a London street corner. Inside, the Doctor and his friends watch the unfamiliar display.

Back on Kembel, the dematerialisation countdown continues from 20.

Sara and Steven are still baffled as they watch what are clearly celebrations going on outside. It is the middle of the night and it looks cold. None of this seems to deter the celebrants. The Doctor has only seen revels like this once before - the night the news of the relief of Mafeking reached England.

The TARDIS materializes next to an Egyptian pyramid on the sun-baked sand. Unlike the familiar craggy contours of the pyramids we know today, this pyramid's sides are smooth and evenly coloured. It is also unfinished, its highest plane more than twice the height of the TARDIS. A dirt ramp runs up one side of it, allowing the thousands of workers access to the site as it rises skyward.

The Dalek time machine is right on their heels, preparing to land in the Egyptian desert in 4 minutes. The Dalek in charge of the expedition confers with Mavic Chen. Chen is responsible for recovery of the core, a task he relishes. The Daleks will kill the time travellers once the core is retrieved. Chen is concerned when it becomes clear that the fugitives are not attempting to take off again. He is certain the Doctor will have detected their pursuit. Why then has he chosen to stand and face the Daleks here?

The Doctor is quickly out of the ship with tool box in hand and is soon hard at work on repairing the damage the Monk did to the lock. Steven watches over him, concerned about the other time machine registering on the ship's instruments. The Doctor believes it is the Monk following them and is not terribly concerned. He should land nearby very shortly. Bored, Steven looks round. He sees piles of building stones along with several ornate statues, sarcophagi, and containers. These are treasures for the pharaoh's final journey to the afterlife. Steven takes a moment to be impressed at the unfinished pyramid. The Doctor asks him for help in fetching a tool, but the young man has no clue what he is being asked for and is of little help. As the Doctor grumpily gets the tool himself and continues working, Steven decides to ascend the dirt ramp. He hopes to gain a better vantage point from which to see the Monk's TARDIS arrive.

It is not long before Steven sees a time machine materialise in the distance. Perhaps one quarter of a mile away. Still believing this to be the Monk, Steven hurries down and tells the Doctor and Sara, who has just emerged from the TARDIS. Sara notes that the pursuing time machine has stopped registering and this gibes with what Steven has seen. The young man is ready to take the initiative and meet the Monk head on, but the Doctor will not go. He has had to strip out the entire lock mechanism in order to fix it and he will not leave the ship here unlocked and unattended. He promises to meet up with the others soon and sends them off with an admonition to be careful. As Steven and Sara go off, another set of eyes watches the Doctor for a moment. Then the man is gone, off at a run.

The stranger is a young Egyptian warrior called Tuthmos. He races to a nearby workshop, where Khephren, supervisor of the pyramid's construction, and Hyksos, leader of warriors, are meeting. Tuthmos urges the other to come with him to see the strangers who lurk around the future tomb of the pharaoh. Fearing that thieves already have designs on the pharaoh's recently-arrived treasures, all three head for the pyramid.

Steven and Sara reach the area where the other time machine has landed, observing from a distance. They can see just a featureless metal box, which Steven thinks is odd. If this is the Monk's TARDIS, it should have changed shape to blend in with its surroundings. The reason for this oddity is soon clear as it is not the Monk, but Mavic Chen who emerges from the time machine, accompanied by Daleks. Steven and Sara turn to run, intending to warn the Doctor, but they are quickly captured by Hyksos' warriors, who have found them here. Hyksos then notices Chen and the Daleks. The warrior is concerned over the number of strangers present here. He orders his soldiers to capture all of them. Unfortunately, the outmatched warriors are exterminated en masse by the Daleks. Those who try to run are pursued. Hyksos and a handful of his men escape, taking Steven and Sara as hostages. Undeterred by this minor inconvenience, the Daleks and Chen spread out in search of the time travellers.

Meanwhile, the Doctor has completed his work on the lock and sets off to find his companions. He ends up inside the pyramid, where surplus building materials are stored, alongside more gifts for the pharaoh to join him in the afterlife. He finds no sign of his companions, but he does hear the familiar sounds of a TARDIS materializing. Ducking out of sight, the Doctor watches as the Monk's ship arrives, disguising itself as a block of brown stone. The Monk exits, orientating himself to his new environment, then moves off in search of the Doctor to exact his revenge. The Doctor goes immediately to inspect the Monk's TARDIS. It suddenly occurs to him that if the Monk has just landed, then it must have been the Daleks who arrived in the desert earlier. But why did he not detect both ships?

Steven and Sara are brought - tightly bound - to Khephren's workshop. Hyksos denounces them as plunderers for invading the pharaoh's tomb and as murderers in league with the "fire-throwing machines". Hyksos decides that more warriors are needed to combat the evil machines and he goes off to the next encampment to recruit more men. Meanwhile, Khephren will gather the workers and move more of the pharaoh's treasure into the pyramid where they will be easier to guard. Steven and Sara protest their innocence to the charges and demand to be released. Tuthmos asks them why the old man was so interested in the blue box near the pyramid. He is under the mistaken belief that the box, sitting as it does just outside the pyramid, is part of the pharaoh's treasure brought here by his slaves to go into the tomb. With that belief, the Doctor is clearly a tomb raider and so are they. Steven tries to set the man straight, but causes him to leave in a huff instead. All the better for Sara, as she has found a shard of broken pottery with a sharp edge. She starts to work on cutting through her bonds.

Meanwhile, the Monk scours the building site for any sign of his enemy, the Doctor following along at a discrete distance. The Monk doesn't seem to be in much of a hurry though, sauntering casually while taking in the sights. However, what he finds instead are the Daleks and Mavic Chen! One of the Daleks is ready to exterminate him on sight, but Chen brazenly pushes the gun away. He has noticed the Monk's anachronistic clothing and his recognition of the Daleks. He has deduced that this is another time traveller. When the Monk confirms this (still being held at gunpoint), Chen knows that his presence here is no coincidence. He badgers the Monk to admit he knows the Doctor. The nervous Monk also admits he has a score to settle with the Doctor - meaning he and the Daleks are on the same side - but he would be very glad to give up his "claim" in order to get away from the Dalek guns as quickly as possible. But Chen will not be deterred. He outlines a plan to use the Monk's friendly rivalry with the Doctor to get the taranium from him. It will be the Monk's responsibility, using whatever means necessary. He bullies the little man into agreeing, making sure he is aware of the Daleks' punishment for failure. The Monk has just one hour to bring back the taranium or he will be exterminated.

Unbeknownst to any of them, the Doctor has witnessed all of this.

All the while wondering how he got himself into this mess, the Monk resumes his search for the Doctor. This time it is with some urgency. He produces an energy detector in order to track down the Doctor's TARDIS quickly. Whilst he is engaged, the Doctor heads back to the Monk's TARDIS, a plan in mind.

Inside the pyramid, the Doctor manages to open the Monk's TARDIS and get inside. Shortly, the non-descript stone block begins to change shape. It finally settles into the form of a police box! Chuckling to himself, the Doctor exits, carrying with him a small piece of circuitry he brought out of the Monk's ship.

It doesn't take Sara long to free Steven. He frees her and together they take care of the guards, including Tuthmos. Steven is again impressed by the woman's fighting skill.

Meanwhile, Khephren has succeeded in bringing more pieces of the pharaoh's treasure inside the unfinished pyramid from the desert outside. One of those is the TARDIS! The Monk finally homes in on the TARDIS here. The Doctor, who has been following him for a while, hides in the shadows, somewhat concerned to discover that his ship has been moved. He waits until the Monk has tried and failed to open the doors before confronting him. The two are quickly back to banter mode, the Monk chiding the Doctor for the incongruous appearance of his TARDIS. The Doctor ripostes sharply. The Monk goes on to brag about the manner in which he evaded the Doctor's instruments while following him. He offers to go inside and show the Doctor how it's done, but the shifty man's ulterior motive is clear. The Doctor simply guesses that the Monk is in league with the Daleks. His guilty response confirms it and he is found out.

The Monk changes tack, telling the Doctor that he was only playing along with Chen and planned to warn him about the Daleks right away. But he conveniently forgot to do so. The Doctor sees through this as well and decides to put the Monk "safely out of the way" before he goes. The Doctor raises his walking stick menacingly and backs the nervous Monk into a corner. The Monk warns the Doctor not to do anything he'll regret later...

When the Monk's hour is up, the Daleks lose patience and prepare a task force to attack. All of the humans will be exterminated.

Steven and Sara reach the TARDIS' landing site undetected. Neither the Doctor nor the ship is there. They follow some tracks in the sand which lead into the pyramid's tomb. There is no sign of the Doctor, but they do find the ship. Its doors are locked and it does not appear that the Doctor is inside, despite their insistent knocking.

A second bandaged hand forces up the lid of the sarcophagus. Soon, a crudely bandaged person climbs out and stands unsteadily before Steven and Sara, mumbling. They realize this is no mummy come to life and start to unravel the bandages. They reveal a relieved Meddling Monk!

On board the Dalek time machine, Chen is trying to council the Daleks to have patience, pushing his luck a bit with his seeming insolence. But they are resolute - the Monk's hour is up and he has not returned with either the taranium or a report. All Daleks will disembark and kill everyone until the core is found. Chen tries to get the Daleks to wait a while longer, saying that flexibility can also lead to victory, but they refuse, pouring out of the ship in force. Chen follows, glad to know that he cannot be held responsible if their plan fails.

Steven and Sara listen to the Monk's story - how he tried to warn the Doctor about the Daleks and then was so rudely attacked and trussed up. They are dubious as to its truth, but all that matters to them now is finding the Doctor and getting out of here. The Monk complains of headache, hoping to "get an aspirin" from the Doctor's TARDIS, but Steven and Sara don't even listen to him. Not trusting him at all, they decide to bring him with them as they resume their search for the Doctor. The Monk, for his part, isn't really that keen to find him!

Their search is fruitless, but their incautious shouts draw Chen and the Daleks right to them. The Monk, deciding it's time to get out of this mess, tries to slip away from Steven and Sara. Unfortunately, he runs right into the Daleks. Shortly Steven and Sara are captured as well. The Daleks are ready to exterminate all 3, but Chen stops them again. He demands the taranium core from the Monk, who fears for his life and so turns the Doctor's companions over as hostages. Steven's distrust of the Monk is now complete. Chen thinks this idea will work, the Doctor's loyalty to his friends strong enough to force him to turn over the core for their safe return. The Daleks are eventually convinced and march their hostages back to the time machine. The Monk, feeling that he has fulfilled his part of the deal, tries to leave. The Daleks of course have other ideas and he is forced at gunpoint to return to the Daleks' time machine.

Meanwhile, Tuthmos has regained consciousness and races to tell Khephren that the prisoners have escaped. Fearing that they will join with the "war machines", Tuthmos wishes to flee, but Khephren urges him to be strong and hold out. The machines are all around and escape would be very difficult. They must wait for Hyksos and the promised reinforcements, hoping they can prevail.

The Daleks have set up a broadcasting system with a range of 7 Earth miles. From this, they will make Chen issue their ultimatum to the Doctor. Ignored for the moment, the hostages talk among themselves. The Monk wishes to be thanked for saving Steven and Sara's lives with his quick thinking, but Steven is ready to wring the Monk's neck. Sara is not so sure of the Monk's betrayal, thinking his story of risking his own life for theirs might be true. But Steven knows the Monk of old and refuses to listen. All of them fall silent as Chen moves forward to deliver the ultimatum.

The message is short and to the point -- Steven and Sara are being held prisoner. The Doctor must return the core or they will die. He is to come to the Dalek time machine immediately.

Outside, the Doctor hears and knows he must act.

Chen's voice booms out loud as thunder over the plateau. Tuthmos thinks it could be the voice of the gods, but Khephren knows better. It is the same mortals who build evil killing machines such as they have seen. Soon, Tuthmos will see their undoing.

Chen and the Daleks prepare to go out and wait for the Doctor. Ignored again for the moment, Sara tosses out the idea of trying to get to the microphone to warn the Doctor off. But Steven knows that it wouldn't stop him - in fact it would probably make him more determined to come. The point is moot, however, when the Doctor arrives outside, shouting for the Daleks' attention.

The Doctor stands some distance away from the entrance to the Dalek ship, but he is out in the open and unprotected. He speaks loudly and boldly, with heavy doses of anger. Chen greets him, their first true face-to-face meeting, and tries to act cordial. All the Doctor wants is to see his friends alive. He shouts his demand again and the Daleks take the initiative to have the three prisoners brought out, alive and unharmed. Chen also dispenses with the pleasantries, demanding the real taranium core. The Doctor agrees to hand it over, but on his terms. Chen initially refuses to listen, but the Doctor reminds him - and the trigger-happy Daleks - that he's got the taranium hidden and they will not get it if he or his friends are harmed. Chen agrees to listen.

The Doctor orders all three prisoners to be brought to a place of his choosing and released. He will hand the core over at that time. Chen and one Dalek only will bring them to the west angle of the great pyramid. It is clear the Doctor doesn't trust any of them, but the Daleks agree to the terms. The Doctor goes off to prepare. Chen is somewhat surprised that the Daleks agreed so readily, but the Daleks assure him that one of them is enough to handle the Doctor's extermination.

Hyksos at last returns. He has brought a small army of warriors along with him. They are already in position to attack the war machines. Khephren and Tuthmos go with him to join the assault.

Meanwhile, the Doctor has retrieved the taranium core - the real one - from the TARDIS.

The Daleks are soon ready to rendezvous with the Doctor. Despite their earlier boast, they are not leaving anything to chance. Several Daleks accompany Chen at a distance in breach of their agreement with the Doctor. The prisoners are marched out at gunpoint. Steven's mind is already working on an escape plan. He warns the Monk not to try any "funny business".

Hyksos and his men watch the group leave their ship. The men move off to get into a better position from which to attack.

Chen and the prisoners and one Dalek reach the pyramid. The others skirt around the west angle so as not to be seen. The prisoners are instructed not to move until ordered to do so by the Daleks. Chen will retrieve the core. The Doctor appears from inside the pyramid, standing slightly above Chen and the others and shielded by several upright stone slabs. Chen moves forward as instructed to meet him, but the Doctor notices a second Dalek lurking nearby and berates Chen for disobeying his conditions. Chen stops moving at the Doctor's angry shout. The Doctor changes plan and orders the hostages released now. He will not release the core until they are free.

Steven, Sara and the Monk all run for cover as soon as they are set free. The Doctor then beckons Chen to join him behind the stones. Just as the Doctor produces the core and starts to hand it over, two Daleks come into view from the side with a clear firing angle. The Doctor hands over the core and dodges into the pyramid in one quick movement. The Daleks start to follow him, but they are stopped when Hyksos and his men attack. Pandemonium breaks out as the warriors shout and toss spears and rocks. Chen hurries for cover as the Daleks move into attack formation and begin firing. The soldiers fall in ones, twos, and large groups. The soldiers do their best, even managing to block one Dalek in with a pile of stones for a moment. But the battle is quickly lost as the Egyptians are overwhelmed with Dalek fire.

Steven and Sara find the Doctor just outside the TARDIS in the tomb. Steven is ecstatic that they seem to have gotten away again, but the Doctor's face is tight and his voice grim. Chen got the real core, and with all the chaos outside it would be impossible to retrieve now. Sara is sure that the Daleks have won. Nothing can stop their invasion plans now.

However, the Doctor produces the small circuit he removed from the Monk's TARDIS. It is the ship's directional unit. With it they may be able to get to Kembel. He is not sure it will work, but Steven doesn't want to listen. He is worried the Daleks will find them if they stay around long. The Doctor reveals that he changed the Monk's TARDIS exterior to look like a police box. The Daleks should find him first! They bustle quickly into the TARDIS, uncaring of the Meddling Monk's location or his fate.

The Monk is pleased he's been able to ditch Steven and Sara and reach his TARDIS. However, he is horrified to see it no longer looks like a stone block but a police box! He is even more horrified to see a pair of Daleks bearing down on him. He barely manages to jump into his ship and dematerialise before the firing begins.

The Daleks vow to pursue the time travellers through all eternity to recover the core, but Chen arrives and proudly produces the core, telling them their search is over. He holds it before him rather grandly and accepts their congratulations. The Daleks and Chen head back to the time machine.

On board the TARDIS, the Doctor is busy wiring the Monk's directional unit into the console. Steven utters a small wish that the Monk manages to get away. Perhaps he's not so bad after all. The Doctor thinks he has, but knows that it will be quite some time before they see him again. Without a directional unit, he'll need to make some major repairs. The Doctor worries that the Mark IV directional unit may not be compatible with his ship. There is a slim chance it will work, but an even greater chance that the increased energy rate will destroy the central column.

The Daleks have returned to their time machine and made the necessary preparations for departure. They dematerialise, headed for Kembel with the real taranium core at last. Chen gazes at the core, his ambition to rule the universe undimmed by these long delays.

Elsewhere, on a desolate, windswept planet of ice, a door opens in the side of a large block of ice. It is the Monk's TARDIS, newly arrived on this harsh world. This is clearly not where the Monk had intended to go. A quick check reveals the Doctor's thievery and now the Monk is as lost in space and time as he is! The Monk vows revenge to the high heavens and then dashes back inside to get warm.

The Doctor finishes his work, worried over the lack of testing. He is hesitant to try the unit, knowing full well the disastrous result that may occur. Steven urges him on impatiently, reminding him that this is their only chance of stopping the Daleks. Resigned to their possible fate, the Doctor instructs Steven to pull the main dematerialisation switch.

The Dalek time machine rematerialises in the control room on Kembel. Chen disembarks with the Dalek task force, even more wildly arrogant than before. He assures the Dalek Supreme that he has checked and this is the real core. He hands it over to be fitted into the time destructor. Chen, of course, takes all the credit for its recovery and takes a veiled swipe at the Daleks' incompetence for losing it in the first place. He is instructed to address the final meeting of the remaining members of the Galactic Alliance, but he takes his time in going. He is unaware of the ironic repetition of Zephon's arrogance not long ago.

When he is gone, the Daleks debate his extermination since he has delivered the taranium. The Dalek Supreme decides to let him live for a while longer - his arrogance and greed have a further use for them...

The Doctor and his friends have survived the explosion. In fact, the only damage was to the directional unit itself, which is only a charred bit of plastic now. The Doctor explains that a built-in safety measure kept the power feedback confined to the unit. But now they cannot reach Kembel and the Daleks can invade and conquer the universe unchecked. The Doctor wonders if they could capture the Daleks' or the Monk's time machine, unaware that they are both gone already. He activates the scanner to look around outside.

What they see is not the inside of the pharaoh's pyramid, but a lush jungle landscape. It looks very like Kembel. If the directional unit burned itself out after they dematerialised, they may have made it after all. The Doctor takes all the credit for their success, infuriating Sara. He grabs his cloak and an impulse compass and goes outside to discover where they are. Steven and Sara follow.

In the council chamber, the few remaining members of the alliance talk amongst themselves. Led by Beaus and Celation, they blame the dangerous delay in their plans squarely on the absent Chen. Celation eggs the group on to see that Chen no longer serves any purpose and calls for a censure motion against him. There seems to be unanimous support for this. But they are stopped when Chen is brought in by the Dalek Supreme to address the meeting. Chen announces that preparations are nearly complete and that the final order to launch the warforce will soon be given.

The representatives are stunned at this acceleration of the time table and that Chen knew this when none of them did. They accuse him of usurping the position of the Dalek Supreme and assuming superiority over them. Their anger surfaces again, led by Beaus. Chen doesn't even hide his perceived authority over the group, telling them they have been "dwarfed" by his contribution. As the assembly rises in protest against him, calling for his arrest, he continues shouting that the others are nothing next to him. It is clear that Chen is either insane or insatiably greedy or both. Either way, the Dalek Supreme clearly set him up to divide the group and to create chaos among them.

Beaus orders Chen's death for betraying them and the rest of the delegates agree, chanting for his death. However, when Representative Gearon makes his way to the place where Chen stands, he is gunned down by Chen without hesitation or remorse. The room goes silent in shock. Chen announces that the Dalek Supreme has given him leadership of the alliance. They will obey his orders.

Steven and Sara traverse the jungle. It is alive with noisy creature just out of sight and the foliage is thick. Steven is on the lookout for the deadly Varga plants the Daleks scattered about, but can see no sign of them. He is less certain now that this is Kembel. But an even more immediate problem is the absence of the Doctor. He is no longer following behind them.

Celation reacts angrily to Chen's announcement of leadership over the council. Chen reiterates his paramount importance to the plan due not only to his contribution of the vital taranium but also due to his favoritism by the Daleks. Turning to confirm this, Chen is horrified to find that the Dalek Supreme is no longer in the conference room. In fact, there are no Daleks at all. The door to the conference room is even locked. Have they hung Chen out to dry? Chen succumbs to a moment of fear, knowing the other delegates mean to kill him, but then he suddenly recovers himself with a strange thought. Chen says that the absence of Daleks here is a sign that they trust him to run the meeting on his own. Anger still seethes among the representatives. Chen presses on, addressing one final issue as if nothing had happened - apportionment of the captured territories after the conquest is complete. He tells them - contrary to all previous arrangements - that the delegates will be allowed to oversee their own galaxies but that is all. It is clear that the rest belongs to the Daleks and Chen. And, Chen adds, they will all be answerable to the Dalek Supreme and to him.

The delegates' protestations of treason are quick, loud, and vehement but are halted when a squad of Daleks glides into the room. All of the representatives - including Chen - are held at gunpoint. The meeting is over. Chen splutters in protest, unable to wrap his warped, egotistical mind around the fact that he may not be a trusted Dalek ally after all. The Daleks cut him off. There will be no further discussion allowed.

Steven and Sara return to the TARDIS in search of the missing Doctor. Steven fears that the Daleks may have already captured him and Sara is offering little help. Even if he has been captured, she says, stopping the invasion must be their first priority. There can't be much time left with Chen now in possession of the core. Steven tries to protest, loyal to the Doctor, but Sara suggests that the Doctor has likely already reached the Dalek city on his own. Either way, they will achieve more going there than looking for the Doctor in the endless jungle. Reluctantly, Steven agrees.

They more forward, following bearing 242 on the impulse compass as the Doctor had instructed. The readings indicate the strongest power source in that direction. As they go, Sara asks for a quick lesson in using the compass, just in case "something" happens to Steven. He is not cheered by her pessimism.

In the Dalek control room, the Dalek Supreme is informed that the representatives have been detained. They are to be destroyed when this HQ is destroyed at the start of the invasion of Earth. The Dalek Supreme orders the invasion countdown to begin.

Steven and Sara reach the source of the power emissions and find the Dalek city. This is Kembel after all. They overlook the landing pad and see all the representatives' spaceships poised for takeoff. Steven thinks they will likely leave ahead of the Daleks' ships in order to collect their forces for the invasion. Perhaps they are not too late after all. Sara is quick to move off but Steven wishes she'd be a bit more cautious. They will do no good for Earth if they get themselves killed. After a brief argument over leadership of their band of two, they head for the city. There they might just be able to stop the Daleks and - hopefully - find the missing Doctor.

They reach the city easily and even manage to enter without difficulty. The city seems completely deserted. There aren't even any guard Daleks posted. Sara thinks this could mean the invasion has already begun, but it seems unlikely. When Steven again brings up the prospect of the Doctor having been captured, she fears this "empty" city could just be a trap to catch them too. Even if that is the case, Steven urges them to press on.

A little further and they arrive in what is clearly the Daleks' control room. It, too, is completely deserted. Whatever is happening, the Daleks must be very sure of themselves to leave this place unguarded. It also must mean that they have the Doctor. They notice that the Daleks' time machine sits idly in one corner of the room. Not willing to test their good luck any further, Steven comes up with a plan to barricade themselves inside the time machine and order the Doctor brought to them. He could then work the ship and take them to Earth to warn the authorities about the Daleks. Sara agrees and acts quickly. She spots some equipment that looks like the voice audio she saw in the Dalek time machine. She rashly sends a message identifying herself and ordering the Doctor to be brought to her. She and Steven are surprised to hear Mavic Chen's voice calling back. He doesn't sound quite as in control as previously. In fact, he sounds furious. Steven asks to speak with the Doctor.

Chen is being held in a rather small detention cell with all of the other representatives and it is not doing good things for his state of mind. The others are still very wary of Chen, even though he appears to be in the same predicament as them. When he identifies Sara and Steven as two of the people who stole the taranium, the others are even more convinced this is some form of deception. They will not let him respond to the call.

Instead, Representative Celation speaks for the prisoners. He identifies the Galactic Alliance and blames Chen's treachery for their incarceration. He asks Steven and Sara to find and release them. Steven is eager to do so, hoping that they know where the Doctor is. Sara hesitates, thinking this bizarre turn of events could all be part of the trap. But there are still no Daleks around and they really have no other choice.

The representatives also fear a trick and threaten to kill Chen if these newcomers prove hostile. Chen for his part is starting to round the twist. All the double-dealing he has perpetrated in this enterprise has not only made him see treachery in the most straightforward events but also blinded him to the truth of things going on around him. He actually thinks that Sara - a Space Security Agent from Earth - could be coming here to free him and restore him as Guardian of the Solar System.

Steven and Sara traverse the seemingly endless corridors in search of the detention cell. They are having no luck.

Despite Chen's ravings, the representatives do hear one thing from him that they agree with. The Daleks have betrayed them and the alliance should use their combined forces to destroy the Daleks.

The imprisoned delegates hear Steven and Sara in the corridor outside and call to them. They find the cell and speak to the galactic rulers through an observation port. Chen demands release but Steven refuses when he sees the Doctor is not with them. He fears they will all simply rejoin the Daleks once freed and conquer the universe. But the outer galaxies' leaders forcefully reiterate their hatred of the Daleks due to their betrayal. They no longer believe that their own galaxies will be spared and vow to destroy the Daleks. Sara believes them and soon convinces Steven. He opens the door, warning them all to return to their galaxies and to warn them of the Daleks' plans. Steven and Sara do not realize the depths of Chen's arrogance and greed. He, too, is allowed to go free with the same warning.

A short time later, Sara and Steven watch as the representatives board their ships and take off. The last one to go is Chen's Spar ship. He seems to be taking his time but at last powers up for take off. However, something goes wrong as the ship rises from its pad. A spark, a flash, and the ship explodes sending shards of metal flying. Steven and Sara don't spare a thought for the death of the evil Chen, but realize it is now up to them to warn Earth. They only hope the other representatives can warn their galaxies fast enough. Steven and Sara must find the Doctor.

Heading back toward the city, the two are stopped by the sounds of movement in the jungle. They dodge into the undergrowth and watch as a Dalek glides by. They have not gone after all. Steven and Sara follow the creature at a safe distance. Eventually, it enters a cave in the base of a small mountain and disappears. Obviously they have another base underground. It is a logical place for their invasion fleet to be sheltered. Steven is certain the Daleks are aware of the representatives' escape as well as Chen's death. They must forget about the Doctor for now and find some way to put the Daleks out of action themselves. Otherwise Earth will still be invaded. They start to head into the cave, only to be stopped by a commanding voice from behind - Mavic Chen!

Chen explains that he arranged the explosion of his ship and was hiding in the jungle when it happened. He is very much alive and still determined - in his own mad way - to be master of the universe. He makes a show of the blaster he holds on them and directs them to enter the cave. He is certain the Daleks will be very pleased to see them.

Steven and Sara are led by Chen to a doorway in the cave wall. It opens onto an empty, featureless corridor - Dalek architecture. As Chen leads them down the corridor, Steven tries to reason with him, foolishly hoping there is still some anti-Dalek sentiment in him. This is clearly not the case and Sara dismisses her former boss as mad. This comment hits perhaps a little too close to home for Chen and he threatens to kill them both right here and now.

Steven wants to know why Chen stayed here when he had the chance to escape. The answer is as startling as it is absurd -- Chen believes that they and the Doctor were planning to infiltrate the Dalek hierarchy and usurp his position in the invasion plan! He has only the Doctor's absence and their seeming "knowledge" of the location of the underground base as evidence, but that seems enough for him. Despite Steven's protestations, he sticks with his wild theory. All the machinations have clearly unbalanced the man and now Sara knows he is mad.

Chen goes on to say that by capturing Steven and Sara and handing them over, he will prove his value to the Daleks and retain his position. While he is speaking, focusing his attention on Sara, Steven makes a move toward him, trying to get his gun. But the nervous Chen is too quick and covers them both. He invites them to carry on down the corridor.

In the control room of the underground complex, the Daleks are making final preparations for their invasion. An assault division of 5000 Daleks awaits launch orders. The fully functional time destructor - a smallish machine of immense power - sits on a pedestal in the control room. All that remains is to have it placed in the lead ship before launch. The Dalek Supreme is informed of the arrival of Chen and the two time travellers. All three are classed as "prisoners" and the Dalek Supreme orders them brought to main control.

Chen has been assigned a Dalek escort to lead him to the control room. But Chen wants to escort the prisoners alone, certain that he will be hailed as a hero to the cause for doing so. He refuses to move until the escort confirms that he alone will bring the prisoners. After a moment, the Dalek confirms this. Chen silences Sara's last attempts to convince him of his folly and urges his prisoners forward with a wave of his blaster.

As he goes, secure in his deluded knowledge that he is invaluable to the Dalek plan, the escort Dalek moves forward to follow him at a distance. Chen is no less a prisoner than Steven and Sara. He simply refused to acknowledge it.

Chen arrives at the control room full of arrogance and bravado, but this time there is more than an air of madness to his words and actions. He announces grandly that once again he and he alone has helped the Daleks with their invasion plans. He seems to expect a round of applause, but the Dalek Supreme matter-of-factly announces that their alliance has ended.

Stunned by this, Chen immediately refuses to believe it, shouting wildly. Only he could have helped them get this far in light of their "absurd incompetence". Only he will decide when the alliance is ended. His pronouncement is greeted with inscrutable silence. Unbelievably, Chen orders the Dalek Supreme to tell his Daleks to obey Chen's commands from now on. More silence, which the deranged Chen interprets as evidence that his order has been carried out. However, when he orders a nearby Dalek to fetch him the latest invasion reports, the creature does not move.

Mavic Chen, former Guardian of the Solar System and architect of the great galactic peace, has let his greed and ambition run wild. The duplicity and conniving which have consumed him for the past 50 years or more have finally destroyed his reason and his sanity. That is the only way to explain his behaviour when he condemns the Dalek Supreme for insubordination and orders its death. He levels his blaster and fires. He seems somehow surprised when the beam does no harm whatsoever to the Dalek. A group of Daleks glides toward him, gunsticks ready. He drops his gun, perhaps the last bit of rational thinking he will ever do.

The Dalek Supreme has had enough of this and orders Chen taken out and exterminated. There is to be no firing in the control room for fear of damaging the time destructor. His mind completely gone, Chen shouts that he is the master of the universe and is immortal! He bolts from the room, pursued by a group of Daleks.

In the midst of the chaos, Steven and Sara have been momentarily forgotten. They cannot get out and so shelter in one corner of the control room. They are shocked to see the Doctor sidling up to them from an unknown direction. He is unharmed and free, and he clearly has a plan. He tells them this is no time for questions and gives Steven a key to the TARDIS. He is to take Sara back to the ship for safety while the Doctor deals with the Daleks. He explains that he found this place by following a Dalek and that he now plans to activate the time destructor!

Chen races down the corridor, Daleks in pursuit. With his addled mind, he really has no destination or plan in mind. His flight is cut short when he rounds a corner and comes face to face with more Daleks. He proclaims himself their ruler and says they cannot kill him. He is wrong. All the Dalek guns fire at once and Mavic Chen dies in agony.

In the empty control room, the Doctor succeeds in activating the time destructor. It emits a strange ticking noise and the atmosphere all around is charged and heavy with energy. The Daleks return and discover this situation. They move to surround the Doctor and his friends, but they are too late. The Daleks dare not fire for fear of damaging the vital time destructor and the Doctor knows this. It is a stalemate for the moment, but escape is still his priority and the Daleks are between them and the door.

The Doctor is in control and orders one Dalek forward to use as a shield. Steven clamps down its gun with the Doctor's stick and the Doctor instructs it to move toward the door. The Doctor brings up the rear carrying the delicate time destructor. Once outside, the Doctor orders Steven and Sara back to the TARDIS immediately. He will follow shortly. Steven reluctantly follows the order, dragging a protesting Sara with him.

They don't get very far before Sara stops and wants to go back. She fears not only for the Doctor's life, but also for the possibility that he might fail to stop the Daleks, whatever his plan is. The only thing she wants to do is see the end of the Daleks so she is determined to go back. But Steven trusts the Doctor and is certain he will succeed in his plan. He continues running out of the base, believing that Sara is behind him. But she does not follow him.

The Doctor manages to shove the escort Dalek back inside the control room, then he closes the door and uses his stick to damage the contact mechanism which controls it. The Daleks are locked in as he runs for his life. The Dalek Supreme activates a base-wide alarm and sets about getting the door unjammed.

Heading out, the Doctor runs into Sara returning for him. He is at first angry with her, knowing he now has one more problem to worry about. But he quickly softens, thinking she may be of help. But he warns her that the time destructor will start to affect her soon. Even on low power, it is very dangerous. They resume their escape, hoping Steven has carried on toward the TARDIS.

Indeed he has already reached the exit and emerged into the jungle. He is safe, but realizes that Sara has not followed him. As he calls for her, he also notices something else -- the jungle is beginning to change. There is a strong wind blowing through the foliage, bending it alarmingly. The jungle seems somehow less alive than before. He continues on toward the TARDIS as the Doctor instructed.

Sara and the Doctor also escape the base, emerging at a different exit than Steven. Sara seems to be wearing down quickly. She looks more haggard and feels more tired than usual. The Doctor worries that she is being affected by the time destructor already, which is accelerating time all around them. They both notice the wind and the change in the foliage. The jungle is less green than it was and many leaves have fallen dryly to the ground. Sara suggests destroying the time destructor but the Doctor knows that is impossible. The machine once activated will continue until the taranium core is finally burnt out. But he does think he might be able to neutralise the effect, if they can reach the TARDIS in time.

The Daleks are able to fix the door circuit and open it. They all pour out of the control room in pursuit of the Doctor.

The effects of the time destructor are increasing all around the Doctor and Sara. The jungle is dying rapidly, turning to dust. All sounds of animal life are gone. There is only a howling wind. It is also affecting the Doctor, who looks much older than usual. He is having trouble running now. But Sara, a mere human being, is having the worst of it. She is ageing rapidly. Her hair has already turned white and her joints ache with the effort of running. The Doctor stops to try and help her, but she urges him on. They are racing against the Daleks as well as the time destructor.

Indeed, the Daleks pour out of the base and into the dying jungle, determined to destroy the Doctor once and for all. However, they too are being affected by the time destructor as they go.

As Sara and the Doctor struggle on, they fight against the howling wind and their own ageing limbs. Both of them are walking, and barely at that. The Doctor seems to be faring a bit better, but is slowing nonetheless. The wind whips fine particles of dust into their faces. Sara falls, but struggles to her feet. She must keep going.

Steven has reached the TARDIS and is safe inside. He has guessed that the time destructor is accelerating the life and death of the planet. He activates the scanner to see once-rich soil turning to dust and sand. There is no sign of his friends and nothing he can do.

Sara and the Doctor can at last see the TARDIS ahead, but it might as well be miles away for all the progress they are making. The Doctor falls, the time destructor falling from his numbing hands. Sara helps him up and tries to move on. But Sara falls once again and this time cannot get back up. She knows she will never get up again. The sand pours over her and she recalls an old proverb she read once -- "dust to dust". It is her last thought as she collapses, her face and limbs thin and skeletal. Steven sees this on the scanner and goes out to try and get to her, but the effects of the time destructor hit him hard and he tires rapidly. He can only watch helplessly as Sara's body disappears, buried in and merging with the dust and sand that was once lush jungle soil.

Steven finds the time destructor on the ground where the Doctor dropped it and frantically adjusts its controls. Nothing seems to change and so he leaves the machine and turns to look for the Doctor, who is now on his knees. The Doctor warns Steven not to touch him; it is too dangerous. He orders Steven to go back to the ship in a strangled yell full of age, pain, and anger. It is a frightening sound.

But Steven will not leave his friend and mentor to die, the man who rescued him from captivity on Mechanus and saved his life more than once. He cannot. Feeling a renewed strength somehow, he grabs the Doctor and together they struggle to reach the TARDIS.

Once inside, the Doctor seems to recover slightly, although his voice still sounds old and far away. He thanks Steven for saving his life, explaining that his adjustment to the time destructor changed its function. Instead of pushing time forward, it is now pushing time backward. That was enough to allow the Doctor to survive. But it was not enough for Sara - or for the jungle outside. Time can go backward for those still alive, but those that are dead stay dead. Sara risked her life to come back and save the Doctor. She died in the effort and no tricks of time can bring her back.

On the scanner, they can see a group of Daleks come into view across the dusty plain. They are struggling against the effects of the time destructor, which only increase as they near it. They try firing but cannot damage the machine. Soon they can no longer control their function as both their metal casings and their organic components are forced to devolve into nothingness. The creatures die with screams of primal agony.

Some time later, the Doctor and Steven exit the TARDIS. All is quiet. The wind has died and the time destructor has ceased functioning - its taranium core finally burnt out. The Daleks have been completely defeated, their "indestructible" armour plating and even their mutated physical bodies reduced to dust mixed with all the other dust on the now-barren planet of Kembel.

But Sara is not here to see the victory she fought so hard for - victory over Chen and the Daleks. But in victory the Doctor and Steven must remember the others who have given their lives for it - especially their friends Brett Vyon and Katarina, along with Sara. The "victory" weighs heavily on both of them as they return to the TARDIS. The Doctor laments the "terrible waste" of it all as he closes the door on this epic battle.